diff --git a/config.js b/config.js
index 44cd440..5321b0c 100644
--- a/config.js
+++ b/config.js
@@ -302,8 +302,9 @@ Number.prototype.div = function (divisor) {
 
 
 function LevelUpTime(level) {  // seconds
-  // 20 minutes per level
-  return 20 * level * 60;
+  // 20 minutes for for level 1
+  // exponential increase after that
+  return Math.round((20 + Math.pow(1.15, level) * 60);
 }