This commit introduces the ability to select and apply body composition formulas (Body Fat, Body Water, LBM) within the measurement type detail screen.

android_app/app/src/main/java/com/health/openscale/core/data/Enums.kt

@@ -399,4 +399,97 @@ enum class ConnectionStatus {
     DISCONNECTING,
     /** A connection attempt failed or connection broke unexpectedly. */
     FAILED
-}
+}
+
+enum class BodyFatFormulaOption {
+    OFF,
+    DEURENBERG_1991,
+    DEURENBERG_1992,
+    EDDY_1976,
+    GALLAGHER_2000_NON_ASIAN,
+    GALLAGHER_2000_ASIAN;
+
+    fun displayName(context: Context) = when (this) {
+        OFF -> context.getString(R.string.formula_off)
+        DEURENBERG_1991 -> context.getString(R.string.formula_bf_deurenberg_1991)
+        DEURENBERG_1992 -> context.getString(R.string.formula_bf_deurenberg_1992)
+        EDDY_1976 -> context.getString(R.string.formula_bf_eddy_1976)
+        GALLAGHER_2000_NON_ASIAN -> context.getString(R.string.formula_bf_gallagher_2000_non_asian)
+        GALLAGHER_2000_ASIAN -> context.getString(R.string.formula_bf_gallagher_2000_asian)
+    }
+
+    fun shortDescription(ctx: Context) = when (this) {
+        OFF -> ctx.getString(R.string.formula_desc_off_short)
+        DEURENBERG_1991 -> ctx.getString(R.string.bf_deurenberg_1991_short)
+        DEURENBERG_1992 -> ctx.getString(R.string.bf_deurenberg_1992_short)
+        EDDY_1976 -> ctx.getString(R.string.bf_eddy_1976_short)
+        GALLAGHER_2000_NON_ASIAN -> ctx.getString(R.string.bf_gallagher_2000_non_asian_short)
+        GALLAGHER_2000_ASIAN -> ctx.getString(R.string.bf_gallagher_2000_asian_short)
+    }
+    fun longDescription(ctx: Context) = when (this) {
+        OFF -> ctx.getString(R.string.formula_desc_off_long)
+        DEURENBERG_1991 -> ctx.getString(R.string.bf_deurenberg_1991_long)
+        DEURENBERG_1992 -> ctx.getString(R.string.bf_deurenberg_1992_long)
+        EDDY_1976 -> ctx.getString(R.string.bf_eddy_1976_long)
+        GALLAGHER_2000_NON_ASIAN -> ctx.getString(R.string.bf_gallagher_2000_non_asian_long)
+        GALLAGHER_2000_ASIAN -> ctx.getString(R.string.bf_gallagher_2000_asian_long)
+    }
+}
+
+enum class BodyWaterFormulaOption {
+    OFF,
+    BEHNKE_1963,
+    DELWAIDE_CRENIER_1973,
+    HUME_WEYERS_1971,
+    LEE_SONG_KIM_2001;
+
+    fun displayName(context: Context) = when (this) {
+        OFF -> context.getString(R.string.formula_off)
+        BEHNKE_1963 -> context.getString(R.string.formula_bw_behnke_1963)
+        DELWAIDE_CRENIER_1973 -> context.getString(R.string.formula_bw_delwaide_crenier_1973)
+        HUME_WEYERS_1971 -> context.getString(R.string.formula_bw_hume_weyers_1971)
+        LEE_SONG_KIM_2001 -> context.getString(R.string.formula_bw_lee_song_kim_2001)
+    }
+
+    fun shortDescription(ctx: Context) = when (this) {
+        OFF -> ctx.getString(R.string.formula_desc_off_short)
+        BEHNKE_1963 -> ctx.getString(R.string.bw_behnke_1963_short)
+        DELWAIDE_CRENIER_1973 -> ctx.getString(R.string.bw_delwaide_crenier_1973_short)
+        HUME_WEYERS_1971 -> ctx.getString(R.string.bw_hume_weyers_1971_short)
+        LEE_SONG_KIM_2001 -> ctx.getString(R.string.bw_lee_song_kim_2001_short)
+    }
+    fun longDescription(ctx: Context) = when (this) {
+        OFF -> ctx.getString(R.string.formula_desc_off_long)
+        BEHNKE_1963 -> ctx.getString(R.string.bw_behnke_1963_long)
+        DELWAIDE_CRENIER_1973 -> ctx.getString(R.string.bw_delwaide_crenier_1973_long)
+        HUME_WEYERS_1971 -> ctx.getString(R.string.bw_hume_weyers_1971_long)
+        LEE_SONG_KIM_2001 -> ctx.getString(R.string.bw_lee_song_kim_2001_long)
+    }
+}
+
+enum class LbmFormulaOption {
+    OFF,
+    BOER_1984,
+    HUME_1966,
+    WEIGHT_MINUS_BODY_FAT;
+
+    fun displayName(context: Context) = when (this) {
+        OFF -> context.getString(R.string.formula_off)
+        BOER_1984 -> context.getString(R.string.formula_lbm_boer_1984)
+        HUME_1966 -> context.getString(R.string.formula_lbm_hume_1966)
+        WEIGHT_MINUS_BODY_FAT -> context.getString(R.string.formula_lbm_weight_minus_body_fat)
+    }
+
+    fun shortDescription(ctx: Context) = when (this) {
+        OFF -> ctx.getString(R.string.formula_desc_off_short)
+        BOER_1984 -> ctx.getString(R.string.lbm_boer_1984_short)
+        HUME_1966 -> ctx.getString(R.string.lbm_hume_1966_short)
+        WEIGHT_MINUS_BODY_FAT -> ctx.getString(R.string.lbm_weight_minus_bf_short)
+    }
+    fun longDescription(ctx: Context) = when (this) {
+        OFF -> ctx.getString(R.string.formula_desc_off_long)
+        BOER_1984 -> ctx.getString(R.string.lbm_boer_1984_long)
+        HUME_1966 -> ctx.getString(R.string.lbm_hume_1966_long)
+        WEIGHT_MINUS_BODY_FAT -> ctx.getString(R.string.lbm_weight_minus_bf_long)
+    }
+}

android_app/app/src/main/java/com/health/openscale/core/facade/SettingsFacade.kt

@@ -31,6 +31,9 @@ import androidx.datastore.preferences.core.stringPreferencesKey
 import androidx.datastore.preferences.core.stringSetPreferencesKey
 import androidx.datastore.preferences.preferencesDataStore
 import com.health.openscale.core.data.BackupInterval
+import com.health.openscale.core.data.BodyFatFormulaOption
+import com.health.openscale.core.data.BodyWaterFormulaOption
+import com.health.openscale.core.data.LbmFormulaOption
 import com.health.openscale.core.data.SmoothingAlgorithm
 import com.health.openscale.core.utils.LogManager
 import dagger.Binds
@@ -89,6 +92,10 @@ object SettingsPreferenceKeys {
     val REMINDER_MINUTE = intPreferencesKey("reminder_minute")
     val REMINDER_DAYS = stringSetPreferencesKey("reminder_days")
 
+    val BODY_FAT_FORMULA_OPTION   = stringPreferencesKey("body_fat_formula_option")
+    val BODY_WATER_FORMULA_OPTION = stringPreferencesKey("body_water_formula_option")
+    val LBM_FORMULA_OPTION        = stringPreferencesKey("lbm_formula_option")
+
     // Context strings for screen-specific settings (can be used as prefixes for dynamic keys)
     const val OVERVIEW_SCREEN_CONTEXT = "overview_screen"
     const val GRAPH_SCREEN_CONTEXT = "graph_screen"
@@ -191,6 +198,15 @@ interface SettingsFacade {
     val reminderDays: Flow<Set<String>>
     suspend fun setReminderDays(days: Set<String>)
 
+    val selectedBodyFatFormula: Flow<BodyFatFormulaOption>
+    suspend fun setSelectedBodyFatFormula(option: BodyFatFormulaOption)
+
+    val selectedBodyWaterFormula: Flow<BodyWaterFormulaOption>
+    suspend fun setSelectedBodyWaterFormula(option: BodyWaterFormulaOption)
+
+    val selectedLbmFormula: Flow<LbmFormulaOption>
+    suspend fun setSelectedLbmFormula(option: LbmFormulaOption)
+
     // Generic Settings Accessors
     /**
      * Observes a setting with the given key name and default value.
@@ -591,6 +607,54 @@ class SettingsFacadeImpl @Inject constructor(
         saveSetting(SettingsPreferenceKeys.REMINDER_DAYS.name, safe)
     }
 
+    override val selectedBodyFatFormula = dataStore.data
+        .catch { exception ->
+            LogManager.e(TAG, "Error reading BODY_FAT_FORMULA_OPTION", exception)
+            if (exception is IOException) emit(emptyPreferences()) else throw exception
+        }
+        .map { prefs ->
+            val raw = prefs[SettingsPreferenceKeys.BODY_FAT_FORMULA_OPTION] ?: BodyFatFormulaOption.OFF.name
+            runCatching { BodyFatFormulaOption.valueOf(raw) }.getOrDefault(BodyFatFormulaOption.OFF)
+        }
+        .distinctUntilChanged()
+
+    override suspend fun setSelectedBodyFatFormula(option: BodyFatFormulaOption) {
+        LogManager.d(TAG, "Setting BODY_FAT_FORMULA_OPTION to: ${option.name}")
+        saveSetting(SettingsPreferenceKeys.BODY_FAT_FORMULA_OPTION.name, option.name)
+    }
+
+    override val selectedBodyWaterFormula = dataStore.data
+        .catch { exception ->
+            LogManager.e(TAG, "Error reading BODY_WATER_FORMULA_OPTION", exception)
+            if (exception is IOException) emit(emptyPreferences()) else throw exception
+        }
+        .map { prefs ->
+            val raw = prefs[SettingsPreferenceKeys.BODY_WATER_FORMULA_OPTION] ?: BodyWaterFormulaOption.OFF.name
+            runCatching { BodyWaterFormulaOption.valueOf(raw) }.getOrDefault(BodyWaterFormulaOption.OFF)
+        }
+        .distinctUntilChanged()
+
+    override suspend fun setSelectedBodyWaterFormula(option: BodyWaterFormulaOption) {
+        LogManager.d(TAG, "Setting BODY_WATER_FORMULA_OPTION to: ${option.name}")
+        saveSetting(SettingsPreferenceKeys.BODY_WATER_FORMULA_OPTION.name, option.name)
+    }
+
+    override val selectedLbmFormula = dataStore.data
+        .catch { exception ->
+            LogManager.e(TAG, "Error reading LBM_FORMULA_OPTION", exception)
+            if (exception is IOException) emit(emptyPreferences()) else throw exception
+        }
+        .map { prefs ->
+            val raw = prefs[SettingsPreferenceKeys.LBM_FORMULA_OPTION] ?: LbmFormulaOption.OFF.name
+            runCatching { LbmFormulaOption.valueOf(raw) }.getOrDefault(LbmFormulaOption.OFF)
+        }
+        .distinctUntilChanged()
+
+    override suspend fun setSelectedLbmFormula(option: LbmFormulaOption) {
+        LogManager.d(TAG, "Setting LBM_FORMULA_OPTION to: ${option.name}")
+        saveSetting(SettingsPreferenceKeys.LBM_FORMULA_OPTION.name, option.name)
+    }
+
     @Suppress("UNCHECKED_CAST")
     override fun <T> observeSetting(keyName: String, defaultValue: T): Flow<T> {
         LogManager.v(TAG, "Observing setting: key='$keyName', type='${defaultValue!!::class.simpleName}'")

android_app/app/src/main/java/com/health/openscale/core/usecase/BodyCompositionUseCases.kt

@@ -0,0 +1,215 @@
+/*
+ * openScale
+ * Copyright (C) 2025 olie.xdev <olie.xdeveloper@googlemail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.health.openscale.core.usecase
+
+import com.health.openscale.core.data.*
+import com.health.openscale.core.facade.SettingsFacade
+import com.health.openscale.core.utils.CalculationUtils
+import com.health.openscale.core.utils.ConverterUtils
+import kotlinx.coroutines.flow.first
+import javax.inject.Inject
+import javax.inject.Singleton
+import kotlin.math.pow
+
+@Singleton
+class BodyCompositionUseCases @Inject constructor(
+    private val settings: SettingsFacade,
+    private val userUseCases: UserUseCases,
+    private val measurementQuery: MeasurementQueryUseCases
+) {
+    /**
+     * Apply selected body-composition formulas for the given measurement.
+     *
+     * Rules:
+     * - If a formula is OFF → leave values untouched (no overwrite, no insert).
+     * - If a formula is ON  → overwrite existing value; insert a new value if missing.
+     * - If computed result is null → do not insert; keep existing value as-is.
+     *
+     * No DB I/O here; caller persists via CRUD.
+     */
+    suspend fun applySelectedFormulasForMeasurement(
+        measurement: Measurement,
+        values: List<MeasurementValue>
+    ): List<MeasurementValue> {
+        val bfOpt  = settings.selectedBodyFatFormula.first()
+        val bwOpt  = settings.selectedBodyWaterFormula.first()
+        val lbmOpt = settings.selectedLbmFormula.first()
+
+        if (bfOpt == BodyFatFormulaOption.OFF &&
+            bwOpt == BodyWaterFormulaOption.OFF &&
+            lbmOpt == LbmFormulaOption.OFF
+        ) return values
+
+        val user  = userUseCases.observeUserById(measurement.userId).first() ?: return values
+        val types = measurementQuery.getAllMeasurementTypes().first()
+        val byKey = types.associateBy { it.key }
+
+        // Anchor: weight (in kg)
+        val weightType = byKey[MeasurementTypeKey.WEIGHT] ?: return values
+        val weightVal  = values.find { it.typeId == weightType.id }?.floatValue ?: return values
+        val weightKg   = when (weightType.unit) {
+            UnitType.KG -> weightVal
+            UnitType.LB -> ConverterUtils.toKilogram(weightVal, WeightUnit.LB)
+            UnitType.ST -> ConverterUtils.toKilogram(weightVal, WeightUnit.ST)
+            else        -> return values
+        }
+
+        val heightCm = user.heightCm.toDouble().takeIf { it > 0.0 } ?: return values
+        val ageYears = CalculationUtils.ageOn(measurement.timestamp, user.birthDate)
+        val isMale   = user.gender == GenderType.MALE
+
+        // BMI (prefer provided, otherwise compute)
+        val bmiType = byKey[MeasurementTypeKey.BMI]
+        val bmiProvided = bmiType?.let { t -> values.find { it.typeId == t.id }?.floatValue }
+        val bmi = bmiProvided?.toDouble() ?: run {
+            val hM = heightCm / 100.0
+            weightKg / (hM.pow(2.0))
+        }
+
+        val out = values.toMutableList()
+
+        // Helper: overwrite existing or insert new value if missing (only if newValue != null)
+        fun upsertFloat(type: MeasurementType, newValue: Float?) {
+            val idx = out.indexOfFirst { it.typeId == type.id }
+            if (idx >= 0) {
+                // Update existing (can set to null)
+                out[idx] = out[idx].copy(floatValue = newValue)
+            } else if (newValue != null) {
+                // Insert new row only when we have a concrete value
+                out.add(
+                    MeasurementValue(
+                        id = 0,
+                        measurementId = measurement.id, // 0 for new; CRUD layer will set final id
+                        typeId = type.id,
+                        floatValue = newValue
+                    )
+                )
+            }
+        }
+
+        // --- BODY FAT (%)
+        byKey[MeasurementTypeKey.BODY_FAT]?.let { type ->
+            if (bfOpt != BodyFatFormulaOption.OFF) {
+                val bf = when (bfOpt) {
+                    BodyFatFormulaOption.DEURENBERG_1991 ->
+                        (1.2 * bmi) + (0.23 * ageYears) - if (isMale) 16.2 else 5.4
+                    BodyFatFormulaOption.DEURENBERG_1992 ->
+                        if (ageYears >= 16)
+                            (1.2 * bmi) + (0.23 * ageYears) - (10.8 * (if (isMale) 1 else 0)) - 5.4
+                        else
+                            (1.294 * bmi) + (0.20 * ageYears) - (11.4 * (if (isMale) 1 else 0)) - 8.0
+                    BodyFatFormulaOption.EDDY_1976 ->
+                        if (isMale) (1.281 * bmi) - 10.13 else (1.48 * bmi) - 7.0
+                    BodyFatFormulaOption.GALLAGHER_2000_NON_ASIAN ->
+                        64.5 - (848.0 / bmi) + (0.079 * ageYears)
+                    BodyFatFormulaOption.GALLAGHER_2000_ASIAN ->
+                        if (isMale) 51.9 - (740.0 / bmi) + (0.029 * ageYears)
+                        else         64.8 - (752.0 / bmi) + (0.016 * ageYears)
+                    BodyFatFormulaOption.OFF -> null
+                }?.coerceAtLeast(0.0)
+
+                val newVal = bf?.toFloat()
+                    ?.coerceIn(0f, 75f)
+                    ?.let { CalculationUtils.roundTo(it) }
+
+                upsertFloat(type, newVal)
+            }
+        }
+
+        // --- BODY WATER (stored either as %, or mass depending on type.unit)
+        byKey[MeasurementTypeKey.WATER]?.let { type ->
+            if (bwOpt != BodyWaterFormulaOption.OFF) {
+                val liters = when (bwOpt) {
+                    BodyWaterFormulaOption.BEHNKE_1963 ->
+                        0.72 * ((if (isMale) 0.204 else 0.18) * (heightCm * heightCm)) / 100.0
+                    BodyWaterFormulaOption.DELWAIDE_CRENIER_1973 ->
+                        0.72 * (-1.976 + 0.907 * weightKg)
+                    BodyWaterFormulaOption.HUME_WEYERS_1971 ->
+                        if (isMale) (0.194786 * heightCm) + (0.296785 * weightKg) - 14.012934
+                        else         (0.34454  * heightCm) + (0.183809 * weightKg) - 35.270121
+                    BodyWaterFormulaOption.LEE_SONG_KIM_2001 ->
+                        if (isMale) -28.3497 + (0.243057 * heightCm) + (0.366248 * weightKg)
+                        else        -26.6224 + (0.262513 * heightCm) + (0.232948 * weightKg)
+                    BodyWaterFormulaOption.OFF -> null
+                }?.coerceAtLeast(0.0)
+
+                val newVal: Float? = liters?.let {
+                    when (type.unit) {
+                        UnitType.PERCENT -> {
+                            val pct = (it / weightKg) * 100.0
+                            CalculationUtils.roundTo(pct.toFloat().coerceIn(0f, 100f))
+                        }
+                        UnitType.KG -> CalculationUtils.roundTo(it.toFloat().coerceAtLeast(0f))
+                        UnitType.LB -> CalculationUtils.roundTo(
+                            ConverterUtils.fromKilogram(it.toFloat(), WeightUnit.LB)
+                        )
+                        UnitType.ST -> CalculationUtils.roundTo(
+                            ConverterUtils.fromKilogram(it.toFloat(), WeightUnit.ST)
+                        )
+                        else -> {
+                            // Default to percent if unit is unexpected
+                            val pct = (it / weightKg) * 100.0
+                            CalculationUtils.roundTo(pct.toFloat().coerceIn(0f, 100f))
+                        }
+                    }
+                }
+
+                upsertFloat(type, newVal)
+            }
+        }
+
+        // --- LBM (mass)
+        byKey[MeasurementTypeKey.LBM]?.let { type ->
+            if (lbmOpt != LbmFormulaOption.OFF) {
+                val lbmKg = when (lbmOpt) {
+                    LbmFormulaOption.WEIGHT_MINUS_BODY_FAT -> {
+                        val bfType = byKey[MeasurementTypeKey.BODY_FAT]
+                        // Prefer freshly computed BF in 'out', fallback to original list
+                        val bfPercent = out.firstOrNull { it.typeId == bfType?.id }?.floatValue
+                            ?: values.firstOrNull { it.typeId == bfType?.id }?.floatValue
+                        bfPercent?.let { weightKg * (1f - it / 100f) }?.toDouble()
+                    }
+                    LbmFormulaOption.BOER_1984 ->
+                        if (isMale) (0.4071 * weightKg) + (0.267 * heightCm) - 19.2
+                        else         (0.252  * weightKg) + (0.473 * heightCm) - 48.3
+                    LbmFormulaOption.HUME_1966 ->
+                        if (isMale) (0.32810 * weightKg) + (0.33929 * heightCm) - 29.5336
+                        else         (0.29569 * weightKg) + (0.41813 * heightCm) - 43.2933
+                    LbmFormulaOption.OFF -> null
+                }?.coerceAtLeast(0.0)
+
+                val newVal = lbmKg?.let {
+                    when (type.unit) {
+                        UnitType.KG -> CalculationUtils.roundTo(it.toFloat())
+                        UnitType.LB -> CalculationUtils.roundTo(
+                            ConverterUtils.fromKilogram(it.toFloat(), WeightUnit.LB)
+                        )
+                        UnitType.ST -> CalculationUtils.roundTo(
+                            ConverterUtils.fromKilogram(it.toFloat(), WeightUnit.ST)
+                        )
+                        else -> CalculationUtils.roundTo(it.toFloat())
+                    }
+                }
+
+                upsertFloat(type, newVal)
+            }
+        }
+
+        return out
+    }
+}

android_app/app/src/main/java/com/health/openscale/core/usecase/MeasurementCrudUseCases.kt

@@ -44,10 +44,11 @@ import javax.inject.Singleton
 @Singleton
 class MeasurementCrudUseCases @Inject constructor(
     @ApplicationContext private val appContext: Context,
-    private val databaseRepository: DatabaseRepository,
+    private val settingsFacade: SettingsFacade,
     private val sync: SyncUseCases,
-    private val settingsFacade: SettingsFacade
-) {
+    private val bodyComposition: BodyCompositionUseCases,
+    private val databaseRepository: DatabaseRepository
+    ) {
     private var lastVibrateTime = 0L
 
     /**
@@ -67,17 +68,19 @@ class MeasurementCrudUseCases @Inject constructor(
         measurement: Measurement,
         values: List<MeasurementValue>
     ): Result<Int> = runCatching {
+        val finalValues : List<MeasurementValue> = bodyComposition.applySelectedFormulasForMeasurement(measurement, values)
+
         if (measurement.id == 0) {
             // Insert path
             val newId = databaseRepository.insertMeasurement(measurement).toInt()
 
-            values.forEach { v ->
+            finalValues.forEach { v ->
                 databaseRepository.insertMeasurementValue(v.copy(measurementId = newId))
             }
 
-            sync.triggerSyncInsert(measurement, values,"com.health.openscale.sync")
-            sync.triggerSyncInsert(measurement, values,"com.health.openscale.sync.oss")
-            sync.triggerSyncInsert(measurement, values,"com.health.openscale.sync.debug")
+            sync.triggerSyncInsert(measurement, finalValues,"com.health.openscale.sync")
+            sync.triggerSyncInsert(measurement, finalValues,"com.health.openscale.sync.oss")
+            sync.triggerSyncInsert(measurement, finalValues,"com.health.openscale.sync.debug")
 
             MeasurementWidget.refreshAll(appContext)
 
@@ -89,7 +92,7 @@ class MeasurementCrudUseCases @Inject constructor(
             databaseRepository.updateMeasurement(measurement)
 
             val existing = databaseRepository.getValuesForMeasurement(measurement.id).first()
-            val newSetIds = values.mapNotNull { if (it.id != 0) it.id else null }.toSet()
+            val newSetIds = finalValues.mapNotNull { if (it.id != 0) it.id else null }.toSet()
             val existingIds = existing.map { it.id }.toSet()
 
             // Delete removed values
@@ -97,7 +100,7 @@ class MeasurementCrudUseCases @Inject constructor(
             toDelete.forEach { id -> databaseRepository.deleteMeasurementValueById(id) }
 
             // Update or insert values
-            values.forEach { v ->
+            finalValues.forEach { v ->
                 val exists = existing.any { it.id == v.id && v.id != 0 }
                 if (exists) {
                     databaseRepository.updateMeasurementValue(v.copy(measurementId = measurement.id))
@@ -106,9 +109,9 @@ class MeasurementCrudUseCases @Inject constructor(
                 }
             }
 
-            sync.triggerSyncUpdate(measurement, values, "com.health.openscale.sync")
-            sync.triggerSyncUpdate(measurement, values,"com.health.openscale.sync.oss")
-            sync.triggerSyncUpdate(measurement, values,"com.health.openscale.sync.debug")
+            sync.triggerSyncUpdate(measurement, finalValues, "com.health.openscale.sync")
+            sync.triggerSyncUpdate(measurement, finalValues,"com.health.openscale.sync.oss")
+            sync.triggerSyncUpdate(measurement, finalValues,"com.health.openscale.sync.debug")
 
             MeasurementWidget.refreshAll(appContext)
 

android_app/app/src/main/java/com/health/openscale/ui/screen/settings/MeasurementTypeDetailScreen.kt

@@ -17,29 +17,27 @@
  */
 package com.health.openscale.ui.screen.settings
 
-import android.R.attr.enabled
-import android.R.attr.label
 import android.widget.Toast
 import androidx.compose.foundation.BorderStroke
 import androidx.compose.foundation.background
-import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.IntrinsicSize
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.heightIn
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
-import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.layout.widthIn
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.material.icons.Icons
-import androidx.compose.material.icons.filled.QuestionMark
 import androidx.compose.material.icons.filled.Save
+import androidx.compose.material.icons.outlined.Info
+import androidx.compose.material.icons.outlined.Warning
 import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.DropdownMenuItem
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.ExposedDropdownMenuBox
@@ -62,20 +60,22 @@ import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.painter.Painter
 import androidx.compose.ui.graphics.toArgb
 import androidx.compose.ui.platform.LocalContext
-import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
 import androidx.navigation.NavController
 import com.health.openscale.R
+import com.health.openscale.core.data.BodyFatFormulaOption
+import com.health.openscale.core.data.BodyWaterFormulaOption
 import com.health.openscale.core.data.InputFieldType
+import com.health.openscale.core.data.LbmFormulaOption
 import com.health.openscale.core.data.MeasurementType
 import com.health.openscale.core.data.MeasurementTypeIcon
 import com.health.openscale.core.data.MeasurementTypeKey
@@ -85,8 +85,16 @@ import com.health.openscale.ui.shared.SharedViewModel
 import com.health.openscale.ui.screen.dialog.ColorPickerDialog
 import com.health.openscale.ui.screen.dialog.IconPickerDialog
 import com.health.openscale.ui.shared.TopBarAction
+import kotlinx.coroutines.launch
 import kotlin.text.lowercase
 
+private sealed interface PendingDialog {
+    data class UnitChange(val from: UnitType, val to: UnitType) : PendingDialog
+    data class FormulaOnBodyFat(val option: BodyFatFormulaOption) : PendingDialog
+    data class FormulaOnBodyWater(val option: BodyWaterFormulaOption) : PendingDialog
+    data class FormulaOnLBM(val option: LbmFormulaOption) : PendingDialog
+}
+
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun MeasurementTypeDetailScreen(
@@ -96,51 +104,29 @@ fun MeasurementTypeDetailScreen(
     settingsViewModel: SettingsViewModel,
 ) {
     val context = LocalContext.current
+    val scope = rememberCoroutineScope()
 
     val measurementTypes by sharedViewModel.measurementTypes.collectAsState()
-    // Stores the original state of the measurement type before any UI changes.
-    // Crucial for the conversion logic to have the true original state.
     val originalExistingType = remember(measurementTypes, typeId) {
         measurementTypes.find { it.id == typeId }
     }
     val isEdit = typeId != -1
 
-    // Determine the MeasurementTypeKey for the allowed units logic.
-    // For new types, it's always CUSTOM; for existing types, it's the type's key.
     val currentMeasurementTypeKey = remember(originalExistingType, isEdit) {
-        if (isEdit) originalExistingType?.key ?: MeasurementTypeKey.CUSTOM
-        else MeasurementTypeKey.CUSTOM
+        if (isEdit) originalExistingType?.key ?: MeasurementTypeKey.CUSTOM else MeasurementTypeKey.CUSTOM
     }
 
-    // Get the list of allowed units based on the key.
-    val allowedUnitsForKey = remember(currentMeasurementTypeKey) {
-        currentMeasurementTypeKey.allowedUnitTypes
-    }
-
-    val allowedInputTypesForKey = remember(currentMeasurementTypeKey) {
-        currentMeasurementTypeKey.allowedInputType
-    }
+    val allowedUnitsForKey = remember(currentMeasurementTypeKey) { currentMeasurementTypeKey.allowedUnitTypes }
+    val allowedInputTypesForKey = remember(currentMeasurementTypeKey) { currentMeasurementTypeKey.allowedInputType }
 
     var name by remember { mutableStateOf(originalExistingType?.getDisplayName(context).orEmpty()) }
-
-    // Safely set selectedUnit. If the existing unit isn't allowed or if no existing unit,
-    // use the first allowed unit.
     var selectedUnit by remember {
-        val initialUnit = originalExistingType?.unit
-        if (initialUnit != null && initialUnit in allowedUnitsForKey) {
-            mutableStateOf(initialUnit)
-        } else {
-            mutableStateOf(allowedUnitsForKey.firstOrNull() ?: UnitType.NONE)
-        }
+        val u = originalExistingType?.unit
+        mutableStateOf(if (u != null && u in allowedUnitsForKey) u else allowedUnitsForKey.firstOrNull() ?: UnitType.NONE)
     }
-
     var selectedInputType by remember {
-        val initialInputType = originalExistingType?.inputType
-        if (initialInputType != null && initialInputType in allowedInputTypesForKey) {
-            mutableStateOf(initialInputType)
-        } else {
-            mutableStateOf(allowedInputTypesForKey.firstOrNull() ?: InputFieldType.FLOAT)
-        }
+        val itp = originalExistingType?.inputType
+        mutableStateOf(if (itp != null && itp in allowedInputTypesForKey) itp else allowedInputTypesForKey.firstOrNull() ?: InputFieldType.FLOAT)
     }
     var selectedColor by remember { mutableStateOf(originalExistingType?.color ?: 0xFFFFA726.toInt()) }
     var selectedIcon by remember { mutableStateOf(originalExistingType?.icon ?: MeasurementTypeIcon.IC_DEFAULT) }
@@ -148,140 +134,220 @@ fun MeasurementTypeDetailScreen(
     var isPinned by remember { mutableStateOf(originalExistingType?.isPinned ?: false) }
     var isOnRightYAxis by remember { mutableStateOf(originalExistingType?.isOnRightYAxis ?: false) }
 
+    val bodyFatFormulaOption by sharedViewModel.selectedBodyFatFormula.collectAsState(BodyFatFormulaOption.OFF)
+    val bodyWaterFormulaOption by sharedViewModel.selectedBodyWaterFormula.collectAsState(BodyWaterFormulaOption.OFF)
+    val lbmFormulaOption by sharedViewModel.selectedLbmFormula.collectAsState(LbmFormulaOption.OFF)
+
+    var bodyFatFormula by remember(bodyFatFormulaOption) { mutableStateOf(bodyFatFormulaOption) }
+    var bodyWaterFormula by remember(bodyWaterFormulaOption) { mutableStateOf(bodyWaterFormulaOption) }
+    var lbmFormula by remember(lbmFormulaOption) { mutableStateOf(lbmFormulaOption) }
+
+    var formulaInfoTitle by remember { mutableStateOf<String?>(null) }
+    var formulaInfoText by remember { mutableStateOf<String?>(null) }
+
+    var pendingDialog by remember { mutableStateOf<PendingDialog?>(null) }
+
     var expandedUnit by remember { mutableStateOf(false) }
     var expandedInputType by remember { mutableStateOf(false) }
     var showColorPicker by remember { mutableStateOf(false) }
     var showIconPicker by remember { mutableStateOf(false) }
 
-    var showConfirmDialog by remember { mutableStateOf(false) }
-    var pendingUpdatedType by remember { mutableStateOf<MeasurementType?>(null) }
-
     val titleEdit = stringResource(R.string.measurement_type_detail_title_edit)
     val titleAdd = stringResource(R.string.measurement_type_detail_title_add)
 
-    val unitDropdownEnabled by remember(allowedUnitsForKey) {
-        derivedStateOf { allowedUnitsForKey.size > 1 }
-    }
-    val inputTypeDropdownEnabled by remember(allowedInputTypesForKey) {
-        derivedStateOf { allowedInputTypesForKey.size > 1 }
-    }
+    val unitDropdownEnabled by remember(allowedUnitsForKey) { derivedStateOf { allowedUnitsForKey.size > 1 } }
+    val inputTypeDropdownEnabled by remember(allowedInputTypesForKey) { derivedStateOf { allowedInputTypesForKey.size > 1 } }
 
     LaunchedEffect(originalExistingType, allowedUnitsForKey) {
-        val currentUnitInExistingType = originalExistingType?.unit
-        if (currentUnitInExistingType != null && currentUnitInExistingType in allowedUnitsForKey) {
-            if (selectedUnit != currentUnitInExistingType) { // Only update if different to avoid recomposition loops
-                selectedUnit = currentUnitInExistingType
-            }
-        } else if (allowedUnitsForKey.isNotEmpty() && selectedUnit !in allowedUnitsForKey) {
-            selectedUnit = allowedUnitsForKey.first()
-        } else if (allowedUnitsForKey.isEmpty() && selectedUnit != UnitType.NONE) {
-            // This case should ideally not be reached if keys are well-defined.
-            selectedUnit = UnitType.NONE
-        }
+        originalExistingType?.unit?.let { if (it in allowedUnitsForKey && it != selectedUnit) selectedUnit = it }
+        if (allowedUnitsForKey.isNotEmpty() && selectedUnit !in allowedUnitsForKey) selectedUnit = allowedUnitsForKey.first()
+        if (allowedUnitsForKey.isEmpty() && selectedUnit != UnitType.NONE) selectedUnit = UnitType.NONE
     }
-
     LaunchedEffect(originalExistingType, allowedInputTypesForKey) {
-        val currentInputTypeInExistingType = originalExistingType?.inputType
-        if (currentInputTypeInExistingType != null && currentInputTypeInExistingType in allowedInputTypesForKey) {
-            if (selectedInputType != currentInputTypeInExistingType) {
-                selectedInputType = currentInputTypeInExistingType
-            }
-        } else if (allowedInputTypesForKey.isNotEmpty() && selectedInputType !in allowedInputTypesForKey) {
-            selectedInputType = allowedInputTypesForKey.first()
-        } else if (allowedInputTypesForKey.isEmpty()) {
-            selectedInputType = InputFieldType.FLOAT
-        }
+        originalExistingType?.inputType?.let { if (it in allowedInputTypesForKey && it != selectedInputType) selectedInputType = it }
+        if (allowedInputTypesForKey.isNotEmpty() && selectedInputType !in allowedInputTypesForKey) selectedInputType = allowedInputTypesForKey.first()
+        if (allowedInputTypesForKey.isEmpty()) selectedInputType = InputFieldType.FLOAT
     }
 
     LaunchedEffect(Unit) {
         sharedViewModel.setTopBarTitle(if (isEdit) titleEdit else titleAdd)
         sharedViewModel.setTopBarAction(
             TopBarAction(icon = Icons.Default.Save, onClick = {
-                if (name.isNotBlank()) {
-                    // When creating the updatedType, use the key of the originalExistingType if it's an edit.
-                    // For new types, it's MeasurementTypeKey.CUSTOM.
-                    val finalKey = if (isEdit) originalExistingType?.key ?: MeasurementTypeKey.CUSTOM else MeasurementTypeKey.CUSTOM
+                if (name.isBlank()) {
+                    Toast.makeText(context, R.string.toast_enter_valid_data, Toast.LENGTH_SHORT).show()
+                    return@TopBarAction
+                }
 
-                    val currentUpdatedType = MeasurementType(
-                        id = originalExistingType?.id ?: 0,
-                        name = name,
-                        icon = selectedIcon,
-                        color = selectedColor,
-                        unit = selectedUnit,
-                        inputType = selectedInputType,
-                        displayOrder = originalExistingType?.displayOrder ?: measurementTypes.size,
-                        isEnabled = isEnabled,
-                        isPinned = isPinned,
-                        key = finalKey, // Use the correct key
-                        isDerived = originalExistingType?.isDerived ?: false,
-                        isOnRightYAxis = isOnRightYAxis
-                    )
+                val finalKey = if (isEdit) originalExistingType?.key ?: MeasurementTypeKey.CUSTOM else MeasurementTypeKey.CUSTOM
 
-                    if (isEdit && originalExistingType != null) {
-                        val unitChanged = originalExistingType.unit != currentUpdatedType.unit
-                        val inputTypesAreFloat =
-                            originalExistingType.inputType == InputFieldType.FLOAT && currentUpdatedType.inputType == InputFieldType.FLOAT
+                val derivedForType = when (currentMeasurementTypeKey) {
+                    MeasurementTypeKey.BODY_FAT -> bodyFatFormula != BodyFatFormulaOption.OFF
+                    MeasurementTypeKey.WATER    -> bodyWaterFormula != BodyWaterFormulaOption.OFF
+                    MeasurementTypeKey.LBM      -> lbmFormula != LbmFormulaOption.OFF
+                    else -> originalExistingType?.isDerived ?: false
+                }
 
-                        if (unitChanged && inputTypesAreFloat) {
-                            pendingUpdatedType = currentUpdatedType
-                            showConfirmDialog = true
-                        } else {
-                            settingsViewModel.updateMeasurementType(currentUpdatedType)
-                            navController.popBackStack()
-                        }
-                    } else {
-                        settingsViewModel.addMeasurementType(currentUpdatedType)
-                        navController.popBackStack()
+                val updatedType = MeasurementType(
+                    id = originalExistingType?.id ?: 0,
+                    name = name,
+                    icon = selectedIcon,
+                    color = selectedColor,
+                    unit = selectedUnit,
+                    inputType = selectedInputType,
+                    displayOrder = originalExistingType?.displayOrder ?: measurementTypes.size,
+                    isEnabled = isEnabled,
+                    isPinned = isPinned,
+                    key = finalKey,
+                    isDerived = derivedForType,
+                    isOnRightYAxis = isOnRightYAxis
+                )
+
+                scope.launch {
+                    when (currentMeasurementTypeKey) {
+                        MeasurementTypeKey.BODY_FAT -> if (bodyFatFormula != bodyFatFormulaOption) sharedViewModel.setSelectedBodyFatFormula(bodyFatFormula)
+                        MeasurementTypeKey.WATER    -> if (bodyWaterFormula != bodyWaterFormulaOption) sharedViewModel.setSelectedBodyWaterFormula(bodyWaterFormula)
+                        MeasurementTypeKey.LBM      -> if (lbmFormula != lbmFormulaOption) sharedViewModel.setSelectedLbmFormula(lbmFormula)
+                        else -> Unit
                     }
+                }
+
+                val unitChanged = isEdit && (originalExistingType?.unit != selectedUnit)
+                val needsConversion =
+                    unitChanged &&
+                            (originalExistingType?.inputType == InputFieldType.FLOAT) &&
+                            (selectedInputType == InputFieldType.FLOAT)
+
+                if (isEdit && originalExistingType != null) {
+                    if (needsConversion) {
+                        settingsViewModel.updateMeasurementTypeWithConversion(
+                            originalType = originalExistingType,
+                            updatedType = updatedType
+                        )
+                    } else {
+                        settingsViewModel.updateMeasurementType(updatedType)
+                    }
+                    navController.popBackStack()
                 } else {
-                    Toast.makeText(context, R.string.toast_enter_valid_data, Toast.LENGTH_SHORT)
-                        .show()
+                    settingsViewModel.addMeasurementType(updatedType)
+                    navController.popBackStack()
                 }
             })
         )
     }
 
-    if (showConfirmDialog && originalExistingType != null && pendingUpdatedType != null) {
+    fun requestFormulaChange(newValue: Any) {
+        val turningOn = when (newValue) {
+            is BodyFatFormulaOption   -> newValue != BodyFatFormulaOption.OFF
+            is BodyWaterFormulaOption -> newValue != BodyWaterFormulaOption.OFF
+            is LbmFormulaOption       -> newValue != LbmFormulaOption.OFF
+            else -> false
+        }
+        if (turningOn) {
+            pendingDialog = when (newValue) {
+                is BodyFatFormulaOption   -> PendingDialog.FormulaOnBodyFat(newValue)
+                is BodyWaterFormulaOption -> PendingDialog.FormulaOnBodyWater(newValue)
+                is LbmFormulaOption       -> PendingDialog.FormulaOnLBM(newValue)
+                else -> null
+            }
+        } else {
+            when (newValue) {
+                is BodyFatFormulaOption   -> { bodyFatFormula = newValue; }
+                is BodyWaterFormulaOption -> { bodyWaterFormula = newValue; }
+                is LbmFormulaOption       -> { lbmFormula = newValue; }
+            }
+        }
+    }
+
+    pendingDialog?.let { dlg ->
+        val titleId = when (dlg) {
+            is PendingDialog.UnitChange -> R.string.measurement_type_dialog_confirm_unit_change_title
+            is PendingDialog.FormulaOnBodyFat,
+            is PendingDialog.FormulaOnBodyWater,
+            is PendingDialog.FormulaOnLBM -> R.string.formula_warning_title
+        }
+
+        val message = when (dlg) {
+            is PendingDialog.UnitChange -> {
+                val typeName = (originalExistingType?.getDisplayName(context) ?: name)
+                val fromName = selectedUnit.displayName.lowercase().replaceFirstChar { it.uppercase() }
+                val toName   = dlg.to.displayName.lowercase().replaceFirstChar { it.uppercase() }
+                context.getString(
+                    R.string.measurement_type_dialog_confirm_unit_change_message,
+                    typeName, fromName, toName
+                )
+            }
+            is PendingDialog.FormulaOnBodyFat,
+            is PendingDialog.FormulaOnBodyWater,
+            is PendingDialog.FormulaOnLBM -> {
+                context.getString(R.string.formula_warning_message)
+            }
+        }
+
         AlertDialog(
-            onDismissRequest = { showConfirmDialog = false },
-            title = { Text(stringResource(R.string.measurement_type_dialog_confirm_unit_change_title)) },
+            onDismissRequest = { pendingDialog = null },
+            icon= {
+                Icon(
+                    imageVector = Icons.Outlined.Warning,
+                    contentDescription = null,
+                    tint = MaterialTheme.colorScheme.error,
+                    modifier = Modifier.size(20.dp)
+                )
+            },
+            title = {
+                Text(
+                    text = stringResource(titleId),
+                    style = MaterialTheme.typography.titleLarge
+                )
+            },
             text = {
                 Text(
-                    stringResource(
-                        R.string.measurement_type_dialog_confirm_unit_change_message,
-                        originalExistingType.getDisplayName(context),
-                        originalExistingType.unit.displayName.lowercase().replaceFirstChar { it.uppercase() },
-                        pendingUpdatedType!!.unit.displayName.lowercase().replaceFirstChar { it.uppercase() }
-                    )
+                    text = message,
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant
                 )
             },
             confirmButton = {
-                TextButton(onClick = {
-                    settingsViewModel.updateMeasurementTypeWithConversion(
-                        originalType = originalExistingType,
-                        updatedType = pendingUpdatedType!!
+                TextButton(
+                    onClick = {
+                        when (dlg) {
+                            is PendingDialog.UnitChange -> {
+                                selectedUnit = dlg.to
+                            }
+                            is PendingDialog.FormulaOnBodyFat -> {
+                                bodyFatFormula = dlg.option
+                            }
+                            is PendingDialog.FormulaOnBodyWater -> {
+                                bodyWaterFormula = dlg.option
+                            }
+                            is PendingDialog.FormulaOnLBM -> {
+                                lbmFormula = dlg.option
+                            }
+                        }
+                        pendingDialog = null
+                    },
+                    colors = ButtonDefaults.textButtonColors(
+                        contentColor = MaterialTheme.colorScheme.error
                     )
-                    showConfirmDialog = false
-                    navController.popBackStack()
-                }) { Text(stringResource(R.string.confirm_button)) }
+                ) {
+                    Text(stringResource(R.string.confirm_button))
+                }
             },
             dismissButton = {
-                TextButton(onClick = { showConfirmDialog = false }) { Text(stringResource(R.string.cancel_button)) }
+                TextButton(onClick = { pendingDialog = null }) {
+                    Text(stringResource(R.string.cancel_button))
+                }
             }
         )
     }
 
+
+
     Column(
-        modifier = Modifier
-            .padding(16.dp)
-            .fillMaxSize(),
+        modifier = Modifier.padding(16.dp).fillMaxSize(),
         verticalArrangement = Arrangement.spacedBy(16.dp)
     ) {
         OutlinedSettingRow(label = stringResource(R.string.measurement_type_label_enabled)) {
-            Switch(
-                checked = isEnabled,
-                onCheckedChange = { isEnabled = it }
-            )
+            Switch(checked = isEnabled, onCheckedChange = { isEnabled = it })
         }
 
         if (!isEdit || (originalExistingType?.key == MeasurementTypeKey.CUSTOM)) {
@@ -295,20 +361,13 @@ fun MeasurementTypeDetailScreen(
 
         OutlinedTextField(
             value = "",
-            onValueChange = {}, // Read-only
+            onValueChange = {},
             label = { Text(stringResource(R.string.measurement_type_label_color)) },
-            modifier = Modifier
-                .fillMaxWidth()
-                .clickable { showColorPicker = true },
+            modifier = Modifier.fillMaxWidth().clickable { showColorPicker = true },
             readOnly = true,
-            enabled = false, // To make it look like a display field that's clickable
+            enabled = false,
             trailingIcon = {
-                Box(
-                    modifier = Modifier
-                        .size(24.dp)
-                        .clip(CircleShape)
-                        .background(Color(selectedColor))
-                )
+                Box(modifier = Modifier.size(24.dp).clip(CircleShape).background(Color(selectedColor)))
             },
             colors = TextFieldDefaults.colors(
                 disabledTextColor = LocalContentColor.current,
@@ -321,18 +380,12 @@ fun MeasurementTypeDetailScreen(
 
         OutlinedTextField(
             value = "",
-            onValueChange = {}, // Read-only
+            onValueChange = {},
             label = { Text(stringResource(R.string.measurement_type_label_icon)) },
-            modifier = Modifier
-                .fillMaxWidth()
-                .clickable { showIconPicker = true },
+            modifier = Modifier.fillMaxWidth().clickable { showIconPicker = true },
             readOnly = true,
-            enabled = false, // To make it look like a display field
-            trailingIcon = {
-                MeasurementIcon(
-                    icon = selectedIcon,
-                )
-            },
+            enabled = false,
+            trailingIcon = { MeasurementIcon(icon = selectedIcon) },
             colors = TextFieldDefaults.colors(
                 disabledTextColor = LocalContentColor.current,
                 disabledIndicatorColor = MaterialTheme.colorScheme.outline,
@@ -342,24 +395,64 @@ fun MeasurementTypeDetailScreen(
             )
         )
 
+        // Formula pickers use local state
+        when (currentMeasurementTypeKey) {
+            MeasurementTypeKey.BODY_FAT -> {
+                FormulaPickerRow(
+                    label = stringResource(R.string.formula_label_body_fat),
+                    currentText = bodyFatFormula.displayName(context),
+                    options = BodyFatFormulaOption.entries,
+                    optionLabel = { it.displayName(context) },
+                    optionSubtitle = { it.shortDescription(context) },
+                    onInfo = { opt ->
+                        formulaInfoTitle = opt.displayName(context)
+                        formulaInfoText  = opt.longDescription(context)
+                    },
+                    onSelect = { requestFormulaChange( it) }
+                )
+            }
+            MeasurementTypeKey.WATER -> {
+                FormulaPickerRow(
+                    label = stringResource(R.string.formula_label_body_water),
+                    currentText = bodyWaterFormula.displayName(context),
+                    options = BodyWaterFormulaOption.entries,
+                    optionLabel = { it.displayName(context) },
+                    optionSubtitle = { it.shortDescription(context) },
+                    onInfo = { opt ->
+                        formulaInfoTitle = opt.displayName(context)
+                        formulaInfoText  = opt.longDescription(context)
+                    },
+                    onSelect = { requestFormulaChange(it) }
+                )
+            }
+            MeasurementTypeKey.LBM -> {
+                FormulaPickerRow(
+                    label = stringResource(R.string.formula_label_lbm),
+                    currentText = lbmFormula.displayName(context),
+                    options = LbmFormulaOption.entries,
+                    optionLabel = { it.displayName(context) },
+                    optionSubtitle = { it.shortDescription(context) },
+                    onInfo = { opt ->
+                        formulaInfoTitle = opt.displayName(context)
+                        formulaInfoText  = opt.longDescription(context)
+                    },
+                    onSelect = { requestFormulaChange(it) }
+                )
+            }
+            else -> Unit
+        }
+
         if (unitDropdownEnabled) {
             ExposedDropdownMenuBox(
                 expanded = expandedUnit && unitDropdownEnabled,
-                onExpandedChange = {
-                    if (unitDropdownEnabled) expandedUnit = !expandedUnit
-                },
+                onExpandedChange = { if (unitDropdownEnabled) expandedUnit = !expandedUnit },
                 modifier = Modifier.fillMaxWidth()
             ) {
                 OutlinedSettingRow(
                     label = stringResource(R.string.measurement_type_label_unit),
                     surfaceModifier = Modifier
-                        .menuAnchor(
-                            type = MenuAnchorType.PrimaryNotEditable,
-                            enabled = unitDropdownEnabled
-                        )
-                        .clickable(enabled = unitDropdownEnabled) {
-                            if (unitDropdownEnabled) expandedUnit = true
-                        },
+                        .menuAnchor(type = MenuAnchorType.PrimaryNotEditable, enabled = unitDropdownEnabled)
+                        .clickable(enabled = unitDropdownEnabled) { if (unitDropdownEnabled) expandedUnit = true },
                     controlContent = {
                         Row(verticalAlignment = Alignment.CenterVertically) {
                             Text(
@@ -367,13 +460,10 @@ fun MeasurementTypeDetailScreen(
                                 style = MaterialTheme.typography.bodyLarge,
                                 color = if (unitDropdownEnabled) MaterialTheme.colorScheme.onSurface else MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.7f)
                             )
-                            if (unitDropdownEnabled) {
-                                ExposedDropdownMenuDefaults.TrailingIcon(expanded = expandedUnit)
-                            }
+                            if (unitDropdownEnabled) ExposedDropdownMenuDefaults.TrailingIcon(expanded = expandedUnit)
                         }
                     }
                 )
-
                 if (unitDropdownEnabled) {
                     ExposedDropdownMenu(
                         expanded = expandedUnit,
@@ -383,19 +473,24 @@ fun MeasurementTypeDetailScreen(
                         allowedUnitsForKey.forEach { unit ->
                             DropdownMenuItem(
                                 text = {
-                                    Box(
-                                        modifier = Modifier.fillMaxWidth(),
-                                        contentAlignment = Alignment.CenterEnd
-                                    ) {
-                                        Text(
-                                            text = unit.displayName,
-                                            modifier = Modifier.padding(end = 32.dp)
-                                        )
+                                    Box(Modifier.fillMaxWidth(), contentAlignment = Alignment.CenterEnd) {
+                                        Text(unit.displayName, modifier = Modifier.padding(end = 32.dp))
                                     }
                                 },
                                 onClick = {
-                                    selectedUnit = unit
                                     expandedUnit = false
+                                    if (unit == selectedUnit) return@DropdownMenuItem
+
+                                    val needsConfirm =
+                                        isEdit &&
+                                                (originalExistingType?.inputType == InputFieldType.FLOAT) &&
+                                                (selectedInputType == InputFieldType.FLOAT)
+
+                                    if (needsConfirm) {
+                                        pendingDialog = PendingDialog.UnitChange(from = selectedUnit, to = unit)
+                                    } else {
+                                        selectedUnit = unit
+                                    }
                                 }
                             )
                         }
@@ -404,36 +499,21 @@ fun MeasurementTypeDetailScreen(
             }
         }
 
-        // InputFieldType Dropdown
         if (inputTypeDropdownEnabled) {
-            ExposedDropdownMenuBox(
-                expanded = expandedInputType,
-                onExpandedChange = { expandedInputType = !expandedInputType }
-            ) {
+            ExposedDropdownMenuBox(expanded = expandedInputType, onExpandedChange = { expandedInputType = !expandedInputType }) {
                 OutlinedTextField(
                     readOnly = true,
                     value = selectedInputType.name.lowercase().replaceFirstChar { it.uppercase() },
                     onValueChange = {},
                     label = { Text(stringResource(R.string.measurement_type_label_input_type)) },
                     trailingIcon = { ExposedDropdownMenuDefaults.TrailingIcon(expanded = expandedInputType) },
-                    modifier = Modifier
-                        .menuAnchor(type = MenuAnchorType.PrimaryNotEditable, enabled = true)
-                        .fillMaxWidth()
+                    modifier = Modifier.menuAnchor(type = MenuAnchorType.PrimaryNotEditable, enabled = true).fillMaxWidth()
                 )
-                ExposedDropdownMenu(
-                    expanded = expandedInputType,
-                    onDismissRequest = { expandedInputType = false }
-                ) {
+                ExposedDropdownMenu(expanded = expandedInputType, onDismissRequest = { expandedInputType = false }) {
                     allowedInputTypesForKey.forEach { type ->
                         DropdownMenuItem(
-                            text = {
-                                Text(
-                                    type.name.lowercase().replaceFirstChar { it.uppercase() })
-                            },
-                            onClick = {
-                                selectedInputType = type
-                                expandedInputType = false
-                            }
+                            text = { Text(type.name.lowercase().replaceFirstChar { it.uppercase() }) },
+                            onClick = { selectedInputType = type; expandedInputType = false }
                         )
                     }
                 }
@@ -441,17 +521,10 @@ fun MeasurementTypeDetailScreen(
         }
 
         OutlinedSettingRow(label = stringResource(R.string.measurement_type_label_pinned)) {
-            Switch(
-                checked = isPinned,
-                onCheckedChange = { isPinned = it }
-            )
+            Switch(checked = isPinned, onCheckedChange = { isPinned = it })
         }
-
         OutlinedSettingRow(label = stringResource(R.string.measurement_type_label_on_right_y_axis)) {
-            Switch(
-                checked = isOnRightYAxis,
-                onCheckedChange = { isOnRightYAxis = it }
-            )
+            Switch(checked = isOnRightYAxis, onCheckedChange = { isOnRightYAxis = it })
         }
     }
 
@@ -462,19 +535,48 @@ fun MeasurementTypeDetailScreen(
             onDismiss = { showColorPicker = false }
         )
     }
-
     if (showIconPicker) {
         IconPickerDialog(
             iconBackgroundColor = Color(selectedColor),
-            onIconSelected = {
-                selectedIcon = it
-                showIconPicker = false
-            },
+            onIconSelected = { selectedIcon = it; showIconPicker = false },
             onDismiss = { showIconPicker = false }
         )
     }
+
+    if (formulaInfoTitle != null && formulaInfoText != null) {
+        AlertDialog(
+            onDismissRequest = { formulaInfoTitle = null; formulaInfoText = null },
+            icon = {
+                Icon(
+                    imageVector = Icons.Outlined.Info,
+                    contentDescription = null,
+                    tint = MaterialTheme.colorScheme.primary,
+                    modifier = Modifier.size(20.dp)
+                )
+            },
+            title = {
+                Text(
+                    text = formulaInfoTitle!!,
+                    style = MaterialTheme.typography.titleLarge
+                )
+            },
+            text = {
+                Text(
+                    text = formulaInfoText!!,
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                )
+            },
+            confirmButton = {
+                TextButton(onClick = { formulaInfoTitle = null; formulaInfoText = null }) {
+                    Text(stringResource(R.string.dialog_ok))
+                }
+            }
+        )
+    }
 }
 
+
 @Composable
 private fun OutlinedSettingRow(
     label: String,
@@ -507,3 +609,93 @@ private fun OutlinedSettingRow(
         }
     }
 }
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun <T> FormulaPickerRow(
+    label: String,
+    currentText: String,
+    options: List<T>,
+    optionLabel: (T) -> String,
+    optionSubtitle: ((T) -> String)? = null,
+    onInfo: ((T) -> Unit)? = null,
+    onSelect: (T) -> Unit
+) {
+    var expanded by remember { mutableStateOf(false) }
+
+    ExposedDropdownMenuBox(
+        expanded = expanded,
+        onExpandedChange = { expanded = !expanded },
+        modifier = Modifier.fillMaxWidth()
+    ) {
+        OutlinedSettingRow(
+            label = label,
+            surfaceModifier = Modifier
+                .menuAnchor(type = MenuAnchorType.PrimaryNotEditable, enabled = true)
+                .clickable { expanded = true },
+            controlContent = {
+                Row(verticalAlignment = Alignment.CenterVertically) {
+                    Text(
+                        text = currentText,
+                        style = MaterialTheme.typography.bodyLarge,
+                        maxLines = 2,
+                        overflow = androidx.compose.ui.text.style.TextOverflow.Ellipsis,
+                        modifier = Modifier
+                            .widthIn(min = 24.dp, max = 240.dp)
+                            .padding(end = 12.dp),
+                        textAlign = androidx.compose.ui.text.style.TextAlign.End
+                    )
+                    ExposedDropdownMenuDefaults.TrailingIcon(expanded = expanded)
+                }
+            }
+        )
+
+        ExposedDropdownMenu(
+            expanded = expanded,
+            onDismissRequest = { expanded = false },
+            modifier = Modifier.exposedDropdownSize(matchTextFieldWidth = true)
+        ) {
+            options.forEach { opt ->
+                DropdownMenuItem(
+                    text = {
+                        Column(
+                            modifier = Modifier.fillMaxWidth(),
+                            horizontalAlignment = Alignment.End
+                        ) {
+                            Text(
+                                optionLabel(opt),
+                                textAlign = androidx.compose.ui.text.style.TextAlign.End
+                            )
+                            optionSubtitle?.let { sub ->
+                                Text(
+                                    sub(opt),
+                                    style = MaterialTheme.typography.bodySmall,
+                                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                                    maxLines = 2,
+                                    overflow = androidx.compose.ui.text.style.TextOverflow.Ellipsis,
+                                    textAlign = androidx.compose.ui.text.style.TextAlign.End
+                                )
+                            }
+                        }
+                    },
+                    trailingIcon = if (onInfo != null) {
+                        {
+                            Icon(
+                                imageVector = Icons.Outlined.Info,
+                                contentDescription = null,
+                                modifier = Modifier
+                                    .size(18.dp)
+                                    .clickable { onInfo(opt) },
+                                tint = MaterialTheme.colorScheme.onSurfaceVariant
+                            )
+                        }
+                    } else null,
+                    onClick = {
+                        expanded = false
+                        onSelect(opt)
+                    }
+                )
+            }
+        }
+    }
+}

android_app/app/src/main/res/values-de/strings.xml

@@ -180,6 +180,52 @@
     <string name="measurement_type_dialog_confirm_unit_change_title">Einheitenänderung bestätigen</string>
     <string name="measurement_type_dialog_confirm_unit_change_message">Wenn Sie die Einheit für \'%1$s\' von %2$s auf %3$s ändern, werden alle vorhandenen Datenpunkte konvertiert. Dieser Vorgang kann einige Zeit dauern und kann nicht einfach rückgängig gemacht werden. Möchten Sie fortfahren?</string>
 
+    <string name="formula_label_body_fat">Körperfett-Formel</string>
+    <string name="formula_label_body_water">Körperwasser-Formel</string>
+    <string name="formula_label_lbm">Magermasse-Formel</string>
+    <string name="formula_warning_title">Formelberechnung</string>
+    <string name="formula_warning_message">Diese Messgröße wird schreibgeschützt und automatisch berechnet. Sie aktualisiert sich bei Änderungen der Basiswerte. Gilt für neue oder bearbeitete Messungen; bestehende bleiben unverändert.</string>
+    <string name="formula_off">Aus</string>
+    <string name="formula_bf_deurenberg_1991">Deurenberg (1991)</string>
+    <string name="formula_bf_deurenberg_1992">Deurenberg (1992)</string>
+    <string name="formula_bf_eddy_1976">Eddy et al. (1976)</string>
+    <string name="formula_bf_gallagher_2000_non_asian">Gallagher (2000) – Nicht-asiatisch</string>
+    <string name="formula_bf_gallagher_2000_asian">Gallagher (2000) – Asiatisch</string>
+    <string name="formula_bw_behnke_1963">Behnke et al. (1963)</string>
+    <string name="formula_bw_delwaide_crenier_1973">Delwaide &amp; Crenier (1973)</string>
+    <string name="formula_bw_hume_weyers_1971">Hume &amp; Weyers (1971)</string>
+    <string name="formula_bw_lee_song_kim_2001">Lee, Song &amp; Kim (2001)</string>
+    <string name="formula_lbm_boer_1984">Boer (1984)</string>
+    <string name="formula_lbm_hume_1966">Hume (1966)</string>
+    <string name="formula_lbm_weight_minus_body_fat">Gewicht − Körperfett</string>
+
+    <string name="formula_desc_off_short">Keine automatische Berechnung</string>
+    <string name="formula_desc_off_long">Diese Messgröße wird nicht automatisch berechnet. Werte können manuell eingegeben werden.</string>
+    <string name="bf_deurenberg_1991_short">Klassische Regression (Erw.)</string>
+    <string name="bf_deurenberg_1991_long">Weit verbreitete Bevölkerungsformel von 1991. Für die Allgemeinbevölkerung gedacht; bei sehr schlanken oder sehr muskulösen Personen ggf. ungenauer.</string>
+    <string name="bf_deurenberg_1992_short">Angepasst für Jugend &amp; Erw.</string>
+    <string name="bf_deurenberg_1992_long">Variante mit Anpassung für jüngere Nutzer. Allgemeine Schätzung; sportliche oder atypische Körperbauten können abweichen.</string>
+    <string name="bf_eddy_1976_short">Frühes, geschlechtsspez. Modell</string>
+    <string name="bf_eddy_1976_long">Ältere Regression mit getrennten Koeffizienten für Männer und Frauen. Einfach, aber nicht für Spezialpopulationen optimiert.</string>
+    <string name="bf_gallagher_2000_non_asian_short">Gallagher (Nicht-asiatisch)</string>
+    <string name="bf_gallagher_2000_non_asian_long">Referenzmodell von 2000 für nicht-asiatische Populationen. Nützliche Basis; Genauigkeit variiert je nach Körpertyp.</string>
+    <string name="bf_gallagher_2000_asian_short">Gallagher (Asiatisch)</string>
+    <string name="bf_gallagher_2000_asian_long">Variante für asiatische Populationen. Verwenden, wenn dies besser zum Nutzerhintergrund passt.</string>
+    <string name="bw_behnke_1963_short">Behnke TBW-Schätzung</string>
+    <string name="bw_behnke_1963_long">Klassische Schätzung des Gesamtkörperwassers. Einfach, jedoch nicht für Athleten oder Randfälle individualisiert.</string>
+    <string name="bw_delwaide_crenier_1973_short">Delwaide &amp; Crenier</string>
+    <string name="bw_delwaide_crenier_1973_long">TBW-Formel mit Fokus auf Körpermasse. Gute allgemeine Schätzung; Präzision variiert mit dem Körpertyp.</string>
+    <string name="bw_hume_weyers_1971_short">Hume–Weyers TBW</string>
+    <string name="bw_hume_weyers_1971_long">Weit verbreitetes TBW-Modell mit Körpergröße und Gewicht, geschlechtsspezifisch.</string>
+    <string name="bw_lee_song_kim_2001_short">Lee–Song–Kim</string>
+    <string name="bw_lee_song_kim_2001_long">Neuere TBW-Schätzung, kalibriert an koreanischen Kollektiven. Sinnvoll, wenn dies zum Nutzer passt.</string>
+    <string name="lbm_boer_1984_short">Boer LBM (klinisch)</string>
+    <string name="lbm_boer_1984_long">Fettfreie Masse, häufig in der Klinik genutzt. Geschlechtsspezifische Regression aus Größe und Gewicht.</string>
+    <string name="lbm_hume_1966_short">Hume LBM</string>
+    <string name="lbm_hume_1966_long">Frühes LBM-Modell. Einfach und verbreitet; für sehr sportliche Körpertypen weniger angepasst.</string>
+    <string name="lbm_weight_minus_bf_short">Gewicht − Körperfett</string>
+    <string name="lbm_weight_minus_bf_long">Berechnet LBM als Gesamtgewicht minus Fettmasse aus der gewählten Körperfettformel. Genauigkeit hängt von der BF-Schätzung ab.</string>
+
     <!-- Bluetooth -->
     <string name="info_bluetooth_connection_error_scale_offline">Verbindung zur Waage fehlgeschlagen, bitte stellen Sie sicher, dass sie eingeschaltet ist.</string>
     <string name="info_step_on_scale">Bitte barfuß auf die Waage steigen</string>

android_app/app/src/main/res/values/strings.xml

@@ -182,6 +182,53 @@
     <string name="measurement_type_dialog_confirm_unit_change_title">Confirm Unit Change</string>
     <string name="measurement_type_dialog_confirm_unit_change_message">Changing the unit for \'%1$s\' from %2$s to %3$s will convert all existing data points. This action may take some time and cannot be easily undone. Do you want to proceed?</string>
 
+    <string name="formula_label_body_fat">Body Fat Formula</string>
+    <string name="formula_label_body_water">Body Water Formula</string>
+    <string name="formula_label_lbm">Lean Body Mass Formula</string>
+    <string name="formula_warning_title">Formula Calculation</string>
+    <string name="formula_warning_message">This metric becomes read-only and auto-calculated. It updates when base values change. Applies to new or edited measurements; existing ones stay unchanged.</string>
+
+    <string name="formula_off">Off</string>
+    <string name="formula_bf_deurenberg_1991">Deurenberg (1991)</string>
+    <string name="formula_bf_deurenberg_1992">Deurenberg (1992)</string>
+    <string name="formula_bf_eddy_1976">Eddy et al. (1976)</string>
+    <string name="formula_bf_gallagher_2000_non_asian">Gallagher (2000) – Non-Asian</string>
+    <string name="formula_bf_gallagher_2000_asian">Gallagher (2000) – Asian</string>
+    <string name="formula_bw_behnke_1963">Behnke et al. (1963)</string>
+    <string name="formula_bw_delwaide_crenier_1973">Delwaide &amp; Crenier (1973)</string>
+    <string name="formula_bw_hume_weyers_1971">Hume &amp; Weyers (1971)</string>
+    <string name="formula_bw_lee_song_kim_2001">Lee, Song &amp; Kim (2001)</string>
+    <string name="formula_lbm_boer_1984">Boer (1984)</string>
+    <string name="formula_lbm_hume_1966">Hume (1966)</string>
+    <string name="formula_lbm_weight_minus_body_fat">Weight − Body Fat</string>
+
+    <string name="formula_desc_off_short">No automatic calculation</string>
+    <string name="formula_desc_off_long">This metric is not auto-calculated. You can enter values manually.</string>
+    <string name="bf_deurenberg_1991_short">Classic regression for adults</string>
+    <string name="bf_deurenberg_1991_long">A widely used population formula from 1991. Suited for general adult populations; may be less accurate for very lean or very muscular individuals.</string>
+    <string name="bf_deurenberg_1992_short">Adjusted for teens &amp; adults</string>
+    <string name="bf_deurenberg_1992_long">Variant that adapts for younger users. A general-purpose estimate; athletic or atypical physiques can deviate.</string>
+    <string name="bf_eddy_1976_short">Early sex-specific model</string>
+    <string name="bf_eddy_1976_long">Older regression with separate coefficients for men and women. Simple and fast but not tailored to special populations.</string>
+    <string name="bf_gallagher_2000_non_asian_short">Gallagher (non-Asian)</string>
+    <string name="bf_gallagher_2000_non_asian_long">Reference model from 2000 for non-Asian populations. Useful baseline; accuracy varies across body types.</string>
+    <string name="bf_gallagher_2000_asian_short">Gallagher (Asian)</string>
+    <string name="bf_gallagher_2000_asian_long">Companion model tuned for Asian populations. Use when this better matches the user’s background.</string>
+    <string name="bw_behnke_1963_short">Behnke TBW estimate</string>
+    <string name="bw_behnke_1963_long">Classic total body water estimate. A simple approach; not individualized for athletes or edge cases.</string>
+    <string name="bw_delwaide_crenier_1973_short">Delwaide &amp; Crenier</string>
+    <string name="bw_delwaide_crenier_1973_long">TBW formula emphasizing body mass. Reasonable general estimate; precision varies with physique.</string>
+    <string name="bw_hume_weyers_1971_short">Hume–Weyers TBW</string>
+    <string name="bw_hume_weyers_1971_long">Common TBW model using height and weight, with sex-specific coefficients.</string>
+    <string name="bw_lee_song_kim_2001_short">Lee–Song–Kim</string>
+    <string name="bw_lee_song_kim_2001_long">Later TBW estimate calibrated on Korean cohorts. Consider if that population match applies.</string>
+    <string name="lbm_boer_1984_short">Boer LBM (clinical)</string>
+    <string name="lbm_boer_1984_long">Lean body mass estimate popular in clinical settings. Sex-specific regression from height and weight.</string>
+    <string name="lbm_hume_1966_short">Hume LBM</string>
+    <string name="lbm_hume_1966_long">Early LBM model. Simple and widely used; not tailored to very athletic builds.</string>
+    <string name="lbm_weight_minus_bf_short">Weight − Body Fat</string>
+    <string name="lbm_weight_minus_bf_long">Computes LBM as total weight minus fat mass derived from the chosen body-fat formula. Accuracy depends on the BF estimate.</string>
+
     <!-- Bluetooth -->
     <string name="info_bluetooth_connection_error_scale_offline">Could not connect to scale, please ensure it is on.</string>
     <string name="info_step_on_scale">Please step barefoot on the scale</string>