[OSM-dev] Size of tiles

[Derick Rethans]

On Mon, 1 Jul 2013, Eric Fischer wrote:

> At the equator, the length of a tile is the circumference of the earth
> (40,075 km) divided by 2^zoom, so a zoom level 19 tile is 76.4 meters on a
> side, for 5837m^2.

That is only true for the North-South sides. For the East-West sides the 
size is:

Northern East-West side:  40075 / (2^zoom) * cos(North°);
Sourthern East-West side: 40075 / (2^zoom) * cos(South°);

cheers,
Derick