Explanation of the UK National Grid

The National Grid is a map reference system covering Great Britain, but not Ireland or the Channel Islands. The X/Y (East/North) axis 0/0 point is south west of Lands End.

Alphabetic 2 letter codes identify 100 Km squares, which subdivide into 10 Km squares numbered 0 to 9 West to East and South to North from the left corner. Eastings are quoted before Northings.

Coordinates of 372.8 East and 168.2 North, would be expressed at increasing accuracy as: ST the prime 100 Km square ie 3-- 1--
ST76 a 10 Km square ie 37- 16-
ST7268 integer coordinates ie 372 168
ST728682 coordinates of 372.8 168.2.

UK 100 Km National Grid squares