OS Grid Reference → WGS 84

OS Grid Reference to latitude and longitude converter

Convert OS Grid References to latitude and longitude individually or in batches, with accepted formats, cell precision and representative-point notes.

Batch coordinate converter

Enter one OS Grid Reference per line.

This reference identifies a cell; conversion uses its south-west corner.

Input example: TQ 30028 80380

0 of 100 references

Results use: latitude, longitude order.

Output example: 51.5072, -0.1276

Numeric coordinates are rounded for display: decimal latitude/longitude to up to 6 decimal places, metre-based coordinates to up to 3, DMS seconds to up to 2, and DDM minutes to up to 4.

About this conversion

Convert OS Grid References made from a two-letter 100 km square and easting and northing digits to WGS 84 latitude and longitude.

Frequently asked questions

What input is accepted?

Enter two grid-square letters followed by 6, 8 or 10 digits. The easting and northing halves must be equal in length; spaces are optional.

What output will I receive?

By default, results show WGS 84 latitude first and longitude second in decimal degrees. Select Reverse coordinate order to show longitude first. Displayed decimal places do not add accuracy to the source cell.

Which axes and units are used?

The reference encodes British National Grid easting before northing. WGS 84 output defaults to latitude then longitude in degrees.

How are precision and datum handled?

OSTN15 is required. The converter uses the grid cell's south-west corner as its representative point; extra decimal places do not exceed the source cell's precision.

Where can I use this coordinate system?

Only valid OS British National Grid squares in Great Britain are supported.

What should I check?

  • Use two valid grid-square letters followed by 6, 8 or 10 digits.
  • Give easting and northing digit groups the same length.
  • Treat the result as the cell's south-west corner, with no more precision than the source reference.

Which point represents an OS Grid cell?

This converter uses the cell's south-west corner as its representative point.

What do 6, 8 and 10 digits mean?

They identify cells of 100 m, 10 m and 1 m respectively.