diff --git a/src/tiledimage.js b/src/tiledimage.js
index 82e35ed7..95ac4f3c 100644
--- a/src/tiledimage.js
+++ b/src/tiledimage.js
@@ -419,6 +419,15 @@ $.extend($.TiledImage.prototype, $.EventSource.prototype, /** @lends OpenSeadrag
         return new $.Point(this.source.dimensions.x, this.source.dimensions.y);
     },
 
+    /**
+     * @returns {OpenSeadragon.Point} The TiledImage's content size, in window coordinates.
+     */
+     getSizeInWindowCoordinates: function() {
+        var topLeft = this.imageToWindowCoordinates(new $.Point(0, 0));
+        var bottomRight = this.imageToWindowCoordinates(this.getContentSize());
+        return new $.Point(bottomRight.x - topLeft.x, bottomRight.y - topLeft.y);
+    },
+
     // private
     _viewportToImageDelta: function( viewerX, viewerY, current ) {
         var scale = (current ? this._scaleSpring.current.value : this._scaleSpring.target.value);
diff --git a/test/modules/tiledimage.js b/test/modules/tiledimage.js
index 46860648..4a075328 100644
--- a/test/modules/tiledimage.js
+++ b/test/modules/tiledimage.js
@@ -41,8 +41,11 @@
         viewer.addHandler('open', function(event) {
             var image = viewer.world.getItemAt(0);
             var contentSize = image.getContentSize();
+            var sizeInWindowCoords = image.getSizeInWindowCoordinates();
             assert.equal(contentSize.x, 500, 'contentSize.x');
             assert.equal(contentSize.y, 2000, 'contentSize.y');
+            assert.equal(sizeInWindowCoords.x, 125, 'sizeInWindowCoords.x');
+            assert.equal(sizeInWindowCoords.y, 500, 'sizeInWindowCoords.y');
 
             checkBounds(assert, image, new OpenSeadragon.Rect(5, 6, 10, 40), 'initial bounds');
 
@@ -74,7 +77,18 @@
             image.setHeight(4);
             checkBounds(assert, image, new OpenSeadragon.Rect(7, 8, 1, 4), 'bounds after width');
 
-            assert.equal(handlerCount, 1, 'correct number of handlers called');
+            viewer.addHandler('zoom', function zoomHandler(event) {
+                var sizeInWindowCoords = image.getSizeInWindowCoordinates();
+                viewer.removeHandler('zoom', zoomHandler);
+                handlerCount++;
+                assert.equal(sizeInWindowCoords.x, 4000, 'sizeInWindowCoords.x after zoom');
+                assert.equal(sizeInWindowCoords.y, 16000, 'sizeInWindowCoords.y after zoom');
+            });
+
+            viewer.viewport.zoomTo(8, null, true);
+
+            assert.equal(handlerCount, 2, 'correct number of handlers called');
+
             done();
         });