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Coordinate transformation tool

Please select the coordinates you wish to transform. If you have a whole batch of coordinates to transform visit our batch transformation page or consider downloading our transformation software here.

This transformation has been updated from OSTN02 & OSGM02 to OSTN15 & OSGM15. For a tool to transform OSGB36 coordinates based on OSTN02 & OSGM02 back to ETRS89 and then on to OSGB36 based on OSTN15 & OSGM15 click here. See this article for full details of the changes.


Degrees, Minutes, Seconds

* Denotes a required field.

Degrees, Decimal Minutes

* Denotes a required field.

Decimal Degrees

* Denotes a required field.


* Denotes a required field.

OSGB36 National Grid

Eastings and Northings

* Denotes a required field.

The Coordinate Transformation Tool transforms GNSS based ETRS89 latitude and longitude or cartesian XYZ coordinates to the equivalent OSGB36 National Grid eastings and northings, and vice-versa, using Ordnance Survey's National Grid Transformation OSTN15. It also transforms GPS ellipsoid heights to orthometric (mean sea level) heights on the relevant Ordnance Survey mapping datum (Ordnance Datum Newlyn for mainland Britain), using the National Geoid Model OSGM15.

For more information on coordinate systems and transformations see our publication A guide to coordinate systems in Great Britain.

Developers interested in raw data and code for OSTN15 & OSGM15 please see this page.

For a software version of the transformation see this page.

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