ZoomLevels

• bei OSM http://wiki.openstreetmap.org/wiki/Zoom_levels
• http://www.openstreetmap.org/#map=15/52.8793/9.0908

The distance represented by one pixel (S) is given by

        S=C*cos(y)/2^(z+8)

where...

    C is the (equatorial) circumference of the Earth
    z is the zoom level
    y is the latitude of where you're interested in the scale.

Make sure your calculator is in degrees mode

• http://leafletjs.com/ http://de.wikipedia.org/wiki/Leaflet
• bei google Maps