EPSG:27700, OSGB36 / British National Grid
The British National Grid on the OSGB36 datum, used by Ordnance Survey and most UK public data. Coordinates are eastings and northings in metres.
Parameters
Read from the PROJ definition the converter above runs.
- Projection
- Transverse Mercator
- Ellipsoid
- Airy 1830
- Shift to WGS 84
- 7 parameters
- Central meridian
- -2°
- Latitude of origin
- 49°
- Scale factor
- 0.999601272
- False easting
- 400,000 m
- False northing
- -100,000 m
- Units
- metres
PROJ definition
+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs
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AI AgentFrequently asked questions
What is EPSG:27700?
The British National Grid on the OSGB36 datum, used by Ordnance Survey and most UK public data. Coordinates are eastings and northings in metres.
What are the units and axis order of EPSG:27700?
Metres, counted from a false origin of 400,000 m east and -100,000 m north. Most GIS software writes easting first, then northing; check the order of your source data when a point lands in the wrong place.
How do I use EPSG:27700 in QGIS?
To show the map in it: Project > Properties > CRS, search 27700. To save a layer in it: right-click the layer, Export > Save Features As, and pick EPSG:27700. Set Layer CRS only labels a file whose system is missing; it does not move the data.
Is EPSG:27700 the same as WGS 84?
No. It sits on the Airy 1830 ellipsoid and needs a 7-parameter shift to reach WGS 84, which the converter applies. Skipping it moves points by tens to hundreds of metres.