Google Maps Radius to Zoom

Maps on Google Maps have an integer “zoom level” which defines the resolution of the current view. Zoom levels between 0 (the lowest zoom level, in which the entire world can be seen on one map) to 21+ (down to individual buildings) are possible within the default roadmap maps view.

Google Maps sets zoom level 0 to encompass the entire earth. Each succeeding zoom level doubles the precision in both horizontal and vertical dimensions. More information on how this is done is available in the Google Maps API documentation.

radiusToZoom: function(radius){ return Math.round(14-Math.log(radius)/Math.LN2);}