diff --git a/calendar/classes/type_base.php b/calendar/classes/type_base.php
index 73671197c8e..a7d52fe2f57 100644
--- a/calendar/classes/type_base.php
+++ b/calendar/classes/type_base.php
@@ -210,4 +210,11 @@ abstract class type_base {
      * @return array the converted date
      */
     public abstract function convert_from_gregorian($year, $month, $day, $hour = 0, $minute = 0);
+
+    /**
+     * This return locale for windows os.
+     *
+     * @return string locale
+     */
+    public abstract function locale_win_charset();
 }
diff --git a/calendar/tests/calendartype_test_example.php b/calendar/tests/calendartype_test_example.php
index e596edf717e..ab725d1d035 100644
--- a/calendar/tests/calendartype_test_example.php
+++ b/calendar/tests/calendartype_test_example.php
@@ -305,4 +305,13 @@ class structure extends type_base {
             'hour' => (int) $hour,
             'minute' => (int) $minute);
     }
+
+    /**
+     * This return locale for windows os.
+     *
+     * @return string locale
+     */
+    public function locale_win_charset() {
+        return get_string('localewincharset', 'langconfig');
+    }
 }
diff --git a/calendar/type/gregorian/classes/structure.php b/calendar/type/gregorian/classes/structure.php
index 0c9ee7d4bde..950d8597533 100644
--- a/calendar/type/gregorian/classes/structure.php
+++ b/calendar/type/gregorian/classes/structure.php
@@ -418,4 +418,13 @@ class structure extends type_base {
 
         return $date;
     }
+
+    /**
+     * This return locale for windows os.
+     *
+     * @return string locale
+     */
+    public function locale_win_charset() {
+        return get_string('localewincharset', 'langconfig');
+    }
 }
diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index 2cf904a3888..c4111947fe5 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -2187,8 +2187,16 @@ function userdate($date, $format = '', $timezone = 99, $fixday = true, $fixhour
  */
 function date_format_string($date, $format, $tz = 99) {
     global $CFG;
+
+    $localewincharset = null;
+    // Get the calendar type user is using.
+    if ($CFG->ostype == 'WINDOWS') {
+        $calendartype = \core_calendar\type_factory::get_calendar_instance();
+        $localewincharset = $calendartype->locale_win_charset();
+    }
+
     if (abs($tz) > 13) {
-        if ($CFG->ostype == 'WINDOWS' and $localewincharset = get_string('localewincharset', 'langconfig')) {
+        if ($localewincharset) {
             $format = core_text::convert($format, 'utf-8', $localewincharset);
             $datestring = strftime($format, $date);
             $datestring = core_text::convert($datestring, $localewincharset, 'utf-8');
@@ -2196,7 +2204,7 @@ function date_format_string($date, $format, $tz = 99) {
             $datestring = strftime($format, $date);
         }
     } else {
-        if ($CFG->ostype == 'WINDOWS' and $localewincharset = get_string('localewincharset', 'langconfig')) {
+        if ($localewincharset) {
             $format = core_text::convert($format, 'utf-8', $localewincharset);
             $datestring = gmstrftime($format, $date);
             $datestring = core_text::convert($datestring, $localewincharset, 'utf-8');
diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index eff9dab4535..e683953c47c 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -52,6 +52,8 @@ information provided here is intended especially for developers.
 * New class introduced to help auto generate zIndex values for modal dialogues. Class "moodle-has-zindex"
   should set on any element which uses a non-default zindex and needs to ensure it doesn't show above a
   dialogue.
+* Date format locale charset for windows server will come from calendar type and for gregorian it will use
+  lang file.
 
 DEPRECATIONS:
 Various previously deprecated functions have now been altered to throw DEBUG_DEVELOPER debugging notices