diff --git a/readme.md b/readme.md
index d39b311..f6d6966 100644
--- a/readme.md
+++ b/readme.md
@@ -889,6 +889,11 @@ Heatfit threaded inserts. Can be pushed into thermoplastics using a soldering ir
 | ```insert_ring3_d(type)``` | Diameter of the bottom ring |
 | ```insert_screw_diameter(type)``` | Screw size |
 
+### Functions
+| Function | Description |
+|:--- |:--- |
+| ```insert_boss_radius(type, wall)``` | Compute the outer radius of an insert boss |
+
 ### Modules
 | Module | Description |
 |:--- |:--- |
diff --git a/vitamins/insert.scad b/vitamins/insert.scad
index e6590d4..9a34b1f 100644
--- a/vitamins/insert.scad
+++ b/vitamins/insert.scad
@@ -93,6 +93,8 @@ module insert_hole(type, counterbore = 0, horizontal = false) { //! Make a hole
         }
 }
 
+function insert_boss_radius(type, wall) = corrected_radius(insert_hole_radius(type)) + wall; //! Compute the outer radius of an insert boss
+
 module insert_boss(type, z, wall = 2 * extrusion_width) { //! Make a boss to take an insert
     render(convexity = 3)
         difference() {