diff --git a/gaboshlib/g_percentage-diff.bashfunc b/gaboshlib/g_percentage-diff.bashfunc
new file mode 100644
index 0000000..091bc9b
--- /dev/null
+++ b/gaboshlib/g_percentage-diff.bashfunc
@@ -0,0 +1,8 @@
+#!/bin/bash
+
+function g_percentage-diff {
+  local g_from=$1
+  local g_to=$2
+  local g_diff=$(echo "scale=8; $g_to-$g_from" | bc | sed 's/^\./0./; s/^-\./-0./')
+  echo "scale=8; 100/$g_from*$g_diff" | bc | sed 's/^\./0./; s/^-\./-0./'
+}