Easting and northing to OSGB grid reference converter

Choose how many digits to retain for each coordinate, from a broad 100 kilometre square to a precise one metre cell. The converter applies standard grid-square lettering and truncates coordinate digits correctly, producing a clean reference such as TQ 300 800 without requiring network access or a coordinate lookup service.

Provide coordinates in the correct grid system

Enter an easting and northing expressed in metres in the British National Grid. An easting measures distance eastward from the grid origin, while a northing measures distance northward. These values are not longitude and latitude, and the converter deliberately does not guess or transform the coordinate system. Before converting, confirm that the source identifies the values as British National Grid, OSGB, or EPSG:27700 coordinates. A plausible-looking pair from another projected system can still produce a plausible-looking grid reference, but it will describe the wrong place. Eastings must be at least zero and less than 700000; northings must be at least zero and less than 1300000. Decimal metre values are accepted, although only whole grid cells can be represented by the selected precision. The calculation is local and deterministic: the same coordinate pair and precision always produce the same text, with no geocoding request, place-name matching, or dependence on a remote map service.

Choose precision for the job

Precision is the number of digits shown for each coordinate inside its 100 kilometre lettered square. Zero returns only the two letters and identifies a 100 kilometre square. One digit per coordinate identifies a 10 kilometre square, two identify a one kilometre square, three identify a 100 metre square, four identify a 10 metre square, and five identify a one metre square. A precision of three therefore creates a conventional reference such as TQ 300 800, with three easting digits and three northing digits. More digits make the cell smaller, but they do not make the source measurement more accurate. Choose a precision that reflects how the coordinate was collected and how the reference will be used. A handheld observation recorded only to 100 metres should not be presented as a one metre position merely because extra digits can be printed. The output keeps leading zeroes, since they are significant parts of a grid reference.

Understand lettering and truncation

The first two characters identify the 100 kilometre National Grid square. The calculation derives those letters directly from the easting and northing square indices and skips the letter I, which is omitted from the grid alphabet to avoid confusion with the numeral one. The remaining numeric groups describe distance east and north within that square. Their order is always easting first, northing second: read along the corridor, then up the stairs. Digits are truncated at the requested precision rather than rounded. This matters near a cell boundary, because a grid reference conventionally identifies the south-west corner of the containing cell. Rounding could incorrectly move the reference into the neighbouring cell. The returned object includes the complete formatted reference, its two-letter square, the separate digit groups when precision is above zero, and the applied precision. This structure supports both direct copying and reliable downstream storage without requiring consumers to split the formatted text themselves.