diff -r cbd7644d99ca -r c6f957fa7442 src/Utils.h
--- a/src/Utils.h	Fri Jul 07 20:17:21 2023 +0200
+++ b/src/Utils.h	Sat Aug 19 16:58:03 2023 +0200
@@ -240,6 +240,15 @@
      * @return Pressure in Bar.
      */
     double GetPressureBar(double gl, double T);
+
+    /**
+     * @brief Calculate Hydrometer (and iSpindel) Correction.
+     * @param mg Measured SG
+     * @param tr Temperature at reading in C
+     * @param tc Calibration temperature in C
+     * @return Corrected SG.
+     */
+    double HydroCorrection(double mg, double tr, double tc);
 }
 
 #endif