I’m using OpenLayers to display a map of the same projection as Google Maps, Bing, etc. (that is, a square Mercator map). As I understand it, to enable this projection, I need to use the sphericalMercator flag. However, this also appears to change the units used by the LonLat method, etc. such that I have to transform from decimal degrees to metres. Is there a way I can use the Mercator projection, but still use decimal degrees in order to specify positions on the map? Depends what you mean by ‘specifying positions on the map’: if you want to add Markers, Vector Features etc., you have to re-project their coordinates, but you can do that within OpenLayers. If you just want specify positions in a ‘read-only way’ (e.g. displaying the current mouse position with the MousePosition Control in a certain coordinate system), you can do so by simply specifying the ‘displayProjection’ parameter of the map. Source.