Grid References

Great Britain is broken up into a grid of squares, each one measuring 100km x100km. Each square has it’s own individual two letter reference prefix. The prefixes NH, NJ, NK, NN or NO are the ones applicable to NESBReC’s area.

These prefixes are found in the corners of OS maps. The squares are further sub-divided into 1km x 1km squares and even further into 100m x 100m squares. These subdivisions are depicted by numbers.

Quote the eastings (west to east) first then the northings (south to north). So, in the example below, the grid reference of the red square is NN613317 and the blue square is NN623308


Remember, think like a squirrel…
along the ground then up the tree!

You can use our interactive map on the online form here to automatically generate your grid reference.

You can also utilise various sites to find and/or check your grid references such as: Multimap ( and select OS Map; or Grab a Grid Reference