How do I convert OS coordinates (X and Y) - Eastings and Northings to longitude and latitude coordinates? For example X and Y below

X (Eastings): 347904

Y (Northings): 287484

  • 1
    Can you clarify that this really is Ordnance Survey? Can you tell us where you got those coordinates, and the spatial reference system identifier if you know it?
    – BradHards
    Mar 3, 2014 at 9:26

1 Answer 1


Assuming that OS mean Ordinance Survey then see http://www.movable-type.co.uk/scripts/latlong-gridref.html and http://www.movable-type.co.uk/scripts/latlong-convert-coords.html . Ther is exelent example howto implement conversion.

Another option if you for systems that use EPSG codes 27700 and 7405 seem to be relevant ids (not necessarily correct). Target srid for WGS84 is 4326 and for OSGB-LL it is 4277. PostGIS , proj4 lib , GDAL for an example support support mentioned srid conversions.

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