Convert easting and northing to latitude and longitude
Paste British National Grid eastings and northings, read latitude and longitude right below. It works the other way too.
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Guide
About this tool
Paste an easting and a northing from the British National Grid and the table gives the latitude and longitude in WGS 84: 530269.90, 179640.72, Big Ben, is 51.5007, -0.1246. To go the other way, swap the two systems and paste latitude and longitude.
How to do it
- From is set to OSGB36 / British National Grid (EPSG:27700) and To to WGS 84, latitude and longitude. For Irish Grid, ITM or a UTM zone, pick it in the From list.
- Paste the coordinates, one point per line, easting first: 530269.90, 179640.72. A space, a comma, a tab or a semicolon between the two numbers all work, and so does a column copied from a spreadsheet.
- Read the latitude and longitude in decimal degrees, with degrees, minutes and seconds next to them. Copy the results or download them as CSV, and check each point on the map.
Worked examples
Three places in Great Britain converted with this tool, from their National Grid easting and northing.
| Place | System | Input | Result |
|---|---|---|---|
| London, Big Ben | EPSG:27700 | 530269.90, 179640.72 | 51.5007000, -0.1246000 (51°30'02.52"N 0°07'28.56"W) |
| Edinburgh Castle | EPSG:27700 | 325107.63, 673491.62 | 55.9486000, -3.2008001 (55°56'54.96"N 3°12'02.88"W) |
| Cardiff Castle | EPSG:27700 | 318080.37, 176589.01 | 51.4823000, -3.1811000 (51°28'56.28"N 3°10'51.96"W) |
Frequently asked questions
What are eastings and northings?
They are distances in metres on a flat grid. On the British National Grid the easting counts metres east of the grid's origin, south-west of the Isles of Scilly, and the northing counts metres north of it. Big Ben is 530,270 m east and 179,641 m north. The easting always comes first.
How do I convert a grid reference with letters, like TQ 30269 79640?
The two letters name a 100 km square. Replace them with the square's leading digits: TQ is 5 for the easting and 1 for the northing, so TQ 30269 79640 becomes 530269, 179640. NT (Edinburgh) is 3 and 6, ST (Cardiff) is 3 and 1, SU is 4 and 1, SJ is 3 and 3. A 6-figure reference such as TQ 302 796 is read to 100 m: 530200, 179600.
Is OSGB36 the same as WGS 84?
No. OSGB36 is the datum of the National Grid and WGS 84 is the one GPS and web maps use. The same point differs by up to about 120 m between them, which is why eastings and northings must be converted, not just rescaled, before they go on Google Maps.
How accurate is the conversion?
About 5 m anywhere in Great Britain. This page uses the standard seven-parameter transformation between OSGB36 and WGS 84. Ordnance Survey's OSTN15 grid reaches 0.1 m and is the one to use for survey work; QGIS applies it when the OSTN15 grid file is installed.
Does this work for Ireland and Northern Ireland?
Irish coordinates use other grids. Choose TM65 / Irish Grid (EPSG:29902) or IRENET95 / Irish Transverse Mercator (EPSG:2157) in the From list, then paste eastings and northings the same way.
How do I convert latitude and longitude to easting and northing?
Press the swap button so From is WGS 84 and To is British National Grid, then paste latitude and longitude: 51.5007, -0.1246 gives 530269.90, 179640.72. A whole list converts at once and downloads as CSV.