diff --git a/ui/jquery.ui.progressbar.js b/ui/jquery.ui.progressbar.js
index 46051d2c92..163bb06cd0 100644
--- a/ui/jquery.ui.progressbar.js
+++ b/ui/jquery.ui.progressbar.js
@@ -102,7 +102,7 @@ $.widget( "ui.progressbar", {
 	},
 
 	_percentage: function() {
-		return this.indeterminate ? 100 : 100 * this.options.value / this.options.max;
+		return this.indeterminate ? 100 : 100 * ( this.options.value - this.min ) / ( this.options.max - this.min );
 	},
 
 	_refreshValue: function() {