Assuming I've a point like this :

POINT (751318 9760879)

This point is in EPSG:27700 coordinate reference system.

How do I convert the point to display in a map with EPSG3857 coordinate reference system ?


I don't use any GIS application. I am developing a web application (using leafletjs ). So I don't want to convert data with a tool,I've to convert in code.

  • 3
    Can you give some more details, which program(s) are you using. You can do a conversion with postgis. – Stefan Jan 6 '14 at 11:15
  • @Stefan I've update my question – Shahin Jan 6 '14 at 11:24
  • 1
    Your sample point is NOT in EPSG:27700. The second value is much too large. I get bogus results if I use the values in either order. So is the point just a sample and not an actual data point? – mkennedy Jan 6 '14 at 17:22
  • @mkennedy Actually it's actual point.Is there any way exist to find out crs of data? – Shahin Jan 7 '14 at 1:47
  • If the point is off the Norwegian coast, it might be in mercator projection, or Google mercator. You have to ask the people where you got the data from. Maybe the units are not metres. – AndreJ Jan 7 '14 at 13:31

For use in Leaflet, there is a projection library:


It calculates coordinate conversions from every known CRS to another.

  • Thank you. It's client side library. Is there any library exist calculate coordinate conversions in C# ? – Shahin Jan 6 '14 at 17:22
  • GDAL should be able to do that: gdal.org/ogr/index.html. But I don't know how that works together with leafletjs. – AndreJ Jan 6 '14 at 18:08
  • This is C++ library. – Shahin Jan 7 '14 at 5:25
  • 1
    You can use C# bindings for GDAL, or you might take a look at Proj4Net. – Petr Krebs Jan 7 '14 at 15:11

you could use http://cs2cs.mygeodata.eu/

it gives for EPSG:3857:

-1775737.37691 65104092.2927

after entering your point coordinates in 27700:

enter image description here

If you try Proj itself, you can adapt the commands used by this online tool.

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