diff -r 3b1510050c9b -r 2246d830a42a www/js/global.js
--- a/www/js/global.js	Thu Mar 19 13:42:59 2020 +0100
+++ b/www/js/global.js	Thu Mar 19 20:41:18 2020 +0100
@@ -1,5 +1,5 @@
 /*****************************************************************************
- * Copyright (C) 2014-2019
+ * Copyright (C) 2014-2020
  *
  * Michiel Broek <mbroek at mbse dot eu>
  *
@@ -1190,3 +1190,16 @@
 }
 
 
+function kettle_cm(vol, kettle_vol, kettle_height) {
+ if ((vol > 0) && (kettle_vol > 0) && (vol <= kettle_vol))
+  return Round(100 * ((1 - vol / kettle_vol) * kettle_height), 1);
+ return 0;
+}
+
+
+function kettle_vol(cm, kettle_vol, kettle_height) {
+ if ((cm >= 0) && (kettle_vol > 0) && (cm <= (kettle_height * 100)))
+  return Round(((kettle_height - (cm / 100)) / kettle_height) * kettle_vol, 1);
+ return 0;
+}
+