diff -r 3a837905bbce -r 66e0b4ef9268 www/js/global.js
--- a/www/js/global.js	Tue Oct 27 19:51:22 2020 +0100
+++ b/www/js/global.js	Sun Dec 20 13:40:56 2020 +0100
@@ -1186,12 +1186,15 @@
 
 
 function lintner_to_kolbach(lintner) {
+ var wk = (3.5 * lintner) - 16;
+ if (wk < 0)
+  return 0;
  return (3.5 * lintner) - 16;
 }
 
 
 function kolbach_to_lintner(kolbach) {
- return (kolbach + 16) / 3.5;
+ return Round((kolbach + 16) / 3.5, 3);
 }