diff --git a/examples/heatmap-earthquakes.html b/examples/heatmap-earthquakes.html
index 1f6a294198..d6ec6f8899 100644
--- a/examples/heatmap-earthquakes.html
+++ b/examples/heatmap-earthquakes.html
@@ -29,7 +29,7 @@
 
       <div class="row-fluid">
 
-        <div class="span12">
+        <div class="span8">
           <h4 id="title">Earthquakes heatmap</h4>
           <p id="shortdesc">Demonstrates the use of a heatmap layer.</p>
           <div id="docs">
@@ -40,8 +40,15 @@
           </div>
           <div id="tags">heatmap, kml, vector, style</div>
         </div>
-      </div>
 
+        <div class="span4">
+          <form>
+            <label>radius size</label>
+            <input id="radius" type="range" min="1" max="50" step="1" value="5"/>
+          </form>
+        </div>
+
+      </div>
     </div>
 
     <script src="../resources/jquery.min.js" type="text/javascript"></script>
diff --git a/examples/heatmap-earthquakes.js b/examples/heatmap-earthquakes.js
index e28ce927b1..0e41408931 100644
--- a/examples/heatmap-earthquakes.js
+++ b/examples/heatmap-earthquakes.js
@@ -5,6 +5,7 @@ goog.require('ol.layer.Tile');
 goog.require('ol.source.KML');
 goog.require('ol.source.Stamen');
 
+var radius = $('#radius');
 
 var vector = new ol.layer.Heatmap({
   source: new ol.source.KML({
@@ -12,7 +13,7 @@ var vector = new ol.layer.Heatmap({
     projection: 'EPSG:3857',
     url: 'data/kml/2012_Earthquakes_Mag5.kml'
   }),
-  radius: 5
+  radius: parseInt(radius.val(), 10)
 });
 
 vector.getSource().on('addfeature', function(event) {
@@ -38,3 +39,8 @@ var map = new ol.Map({
     zoom: 2
   })
 });
+
+
+radius.on('input', function() {
+  vector.setRadius(parseInt(radius.val(), 10));
+});
diff --git a/src/ol/layer/heatmaplayer.js b/src/ol/layer/heatmaplayer.js
index e14c9d1fc6..dd65d7906b 100644
--- a/src/ol/layer/heatmaplayer.js
+++ b/src/ol/layer/heatmaplayer.js
@@ -16,7 +16,8 @@ goog.require('ol.style.Style');
  * @enum {string}
  */
 ol.layer.HeatmapLayerProperty = {
-  GRADIENT: 'gradient'
+  GRADIENT: 'gradient',
+  RADIUS: 'radius'
 };
 
 
@@ -52,22 +53,42 @@ ol.layer.Heatmap = function(opt_options) {
    */
   this.gradient_ = null;
 
+  /**
+   * @private
+   * @type {number}
+   */
+  this.blur_ = goog.isDef(options.blur) ? options.blur : 15;
+
+  /**
+   * @private
+   * @type {number}
+   */
+  this.shadow_ = goog.isDef(options.shadow) ? options.shadow : 250;
+
+  /**
+   * @private
+   * @type {string|undefined}
+   */
+  this.circleImage_ = undefined;
+
+  /**
+   * @private
+   * @type {Array.<Array.<ol.style.Style>>}
+   */
+  this.styleCache_ = null;
+
   goog.events.listen(this,
       ol.Object.getChangeEventType(ol.layer.HeatmapLayerProperty.GRADIENT),
       this.handleGradientChanged_, false, this);
 
+  goog.events.listen(this,
+      ol.Object.getChangeEventType(ol.layer.HeatmapLayerProperty.RADIUS),
+      this.handleStyleChanged_, false, this);
+
   this.setGradient(goog.isDef(options.gradient) ?
       options.gradient : ol.layer.Heatmap.DEFAULT_GRADIENT);
 
-  var circle = ol.layer.Heatmap.createCircle_(
-      goog.isDef(options.radius) ? options.radius : 8,
-      goog.isDef(options.blur) ? options.blur : 15,
-      goog.isDef(options.shadow) ? options.shadow : 250);
-
-  /**
-   * @type {Array.<Array.<ol.style.Style>>}
-   */
-  var styleCache = new Array(256);
+  this.setRadius(goog.isDef(options.radius) ? options.radius : 8);
 
   var weight = goog.isDef(options.weight) ? options.weight : 'weight';
   var weightFunction;
@@ -80,25 +101,25 @@ ol.layer.Heatmap = function(opt_options) {
   }
   goog.asserts.assert(goog.isFunction(weightFunction));
 
-  this.setStyle(function(feature, resolution) {
+  this.setStyle(goog.bind(function(feature, resolution) {
     var weight = weightFunction(feature);
     var opacity = goog.isDef(weight) ? goog.math.clamp(weight, 0, 1) : 1;
     // cast to 8 bits
     var index = (255 * opacity) | 0;
-    var style = styleCache[index];
+    var style = this.styleCache_[index];
     if (!goog.isDef(style)) {
       style = [
         new ol.style.Style({
           image: new ol.style.Icon({
             opacity: opacity,
-            src: circle
+            src: this.circleImage_
           })
         })
       ];
-      styleCache[index] = style;
+      this.styleCache_[index] = style;
     }
     return style;
-  });
+  }, this));
 
   // For performance reasons, don't sort the features before rendering.
   // The render order is not relevant for a heatmap representation.
@@ -142,21 +163,19 @@ ol.layer.Heatmap.createGradient_ = function(colors) {
 
 
 /**
- * @param {number} radius Radius size in pixel.
- * @param {number} blur Blur size in pixel.
- * @param {number} shadow Shadow offset size in pixel.
  * @return {string}
  * @private
  */
-ol.layer.Heatmap.createCircle_ = function(radius, blur, shadow) {
-  var halfSize = radius + blur + 1;
+ol.layer.Heatmap.prototype.createCircle_ = function() {
+  var radius = this.getRadius();
+  var halfSize = radius + this.blur_ + 1;
   var size = 2 * halfSize;
   var context = ol.dom.createCanvasContext2D(size, size);
-  context.shadowOffsetX = context.shadowOffsetY = shadow;
-  context.shadowBlur = blur;
+  context.shadowOffsetX = context.shadowOffsetY = this.shadow_;
+  context.shadowBlur = this.blur_;
   context.shadowColor = '#000';
   context.beginPath();
-  var center = halfSize - shadow;
+  var center = halfSize - this.shadow_;
   context.arc(center, center, radius, 0, Math.PI * 2, true);
   context.fill();
   return context.canvas.toDataURL();
@@ -178,6 +197,20 @@ goog.exportProperty(
     ol.layer.Heatmap.prototype.getGradient);
 
 
+/**
+ * @return {number} Radius size in pixel.
+ * @api
+ * @observable
+ */
+ol.layer.Heatmap.prototype.getRadius = function() {
+  return /** @type {number} */ (this.get(ol.layer.HeatmapLayerProperty.RADIUS));
+};
+goog.exportProperty(
+    ol.layer.Heatmap.prototype,
+    'getRadius',
+    ol.layer.Heatmap.prototype.getRadius);
+
+
 /**
  * @private
  */
@@ -186,6 +219,16 @@ ol.layer.Heatmap.prototype.handleGradientChanged_ = function() {
 };
 
 
+/**
+ * @private
+ */
+ol.layer.Heatmap.prototype.handleStyleChanged_ = function() {
+  this.circleImage_ = this.createCircle_();
+  this.styleCache_ = new Array(256);
+  this.changed();
+};
+
+
 /**
  * @param {ol.render.Event} event Post compose event
  * @private
@@ -221,3 +264,17 @@ goog.exportProperty(
     ol.layer.Heatmap.prototype,
     'setGradient',
     ol.layer.Heatmap.prototype.setGradient);
+
+
+/**
+ * @param {number} radius Radius size in pixel.
+ * @api
+ * @observable
+ */
+ol.layer.Heatmap.prototype.setRadius = function(radius) {
+  this.set(ol.layer.HeatmapLayerProperty.RADIUS, radius);
+};
+goog.exportProperty(
+    ol.layer.Heatmap.prototype,
+    'setRadius',
+    ol.layer.Heatmap.prototype.setRadius);