British National Grid (OSGB36) to Lat/Long Converter

Convert Ordnance Survey British National Grid (EPSG:27700) Eastings/Northings or National Grid References (e.g. TQ 300 800) to WGS84 Latitude and Longitude.

Easting, Northing (or 6-figure Grid Ref e.g. TQ300800):

About British National Grid (OSGB36 / EPSG:27700)

The British National Grid (BNG) is the official coordinate system created by Ordnance Survey for Great Britain. It uses a Transverse Mercator projection based on the Airy 1830 ellipsoid with false origin southwest of the Isles of Scilly (49°N, 2°W).

Converting between BNG and GPS (WGS84) requires an helmert datum transformation or OSTN15 grid shift to avoid systematic position errors of up to 120 metres.

Common UK Grid Reference Examples

Location	BNG Easting, Northing	Grid Reference	WGS84 Lat, Long
Big Ben, London	530059, 179633	TQ 3005 7963	51.5007° N, 0.1246° W
Edinburgh Castle	325200, 673500	NT 2520 7350	55.9486° N, 3.1999° W
Snowdon Summit	260970, 354370	SH 6097 5437	53.0685° N, 4.0763° W