I have added a online tile source in the 'XYZ Tiles' option, and added it as a layer, which works fine. But im trying to understand where the extents shown in the layer properties is coming from? When I just loaded a simple JPEG as a raster background, my coord system and extents was just the pixels of the background, and origin 0,0 in a corner. But now with the tile source the origin is the middle (which is not a big deal) but the extents are like (big, see image) it would seem totally disconnected from the actual image widths, which is throwing out my coord system. enter image description here

1 Answer 1


The coordinates for the zxy tile system are based off of the Web Mercator Projection: 3857. More information on the coordinate system is here:


You bounds are covering the whole world, and the width and height are the size of the world, when approximating a sphere.

40075016 meters is basically the circumference of the earth at the equator: https://en.wikipedia.org/wiki/Earth%27s_circumference

0,0 in the coordinate system is where the prime meridian meets the equator. Sometimes referred to as Null Island: https://en.wikipedia.org/wiki/Null_Island

  • Ah ok, makes sense, thanks, is there some way to change this ? Im making a flat fictional game map, so not spherical, and would prefer it say 0-256 for example. Jul 10, 2019 at 23:50

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