diff --git a/lib/OpenLayers/Control/ScaleLine.js b/lib/OpenLayers/Control/ScaleLine.js
index 935d653a95..9fc243bf71 100644
--- a/lib/OpenLayers/Control/ScaleLine.js
+++ b/lib/OpenLayers/Control/ScaleLine.js
@@ -154,13 +154,16 @@ OpenLayers.Control.ScaleLine = OpenLayers.Class(OpenLayers.Control, {
             return;
         }
 
+        var curMapUnits = this.map.units;
+        var inches = OpenLayers.INCHES_PER_UNIT;
+
         // convert maxWidth to map units
-        var maxSizeData = this.maxWidth * res;  
+        var maxSizeData = this.maxWidth * res * inches[curMapUnits];  
 
         // decide whether to use large or small scale units     
         var topUnits;
         var bottomUnits;
-        if(maxSizeData > 0.1) {
+        if(maxSizeData > 100000) {
             topUnits = this.topOutUnits;
             bottomUnits = this.bottomOutUnits;
         } else {
@@ -169,10 +172,8 @@ OpenLayers.Control.ScaleLine = OpenLayers.Class(OpenLayers.Control, {
         }
 
         // and to map units units
-        var curMapUnits = this.map.units;
-        var inches = OpenLayers.INCHES_PER_UNIT;
-        var topMax = maxSizeData * inches[curMapUnits] / inches[topUnits];
-        var bottomMax = maxSizeData * inches[curMapUnits] / inches[bottomUnits];
+        var topMax = maxSizeData / inches[topUnits];
+        var bottomMax = maxSizeData / inches[bottomUnits];
 
         // now trim this down to useful block length
         var topRounded = this.getBarLen(topMax);