GB Locate

GB Locate allows conversion to and from Latitude/Longitude to OS National Grid reference for Great Britain (OSGB36). This application can also display your current grid location, latitude/longitude and altitude by using the built in GPS and wireless services.

This application proves useful if you have found somewhere on an OS map and want to input the location into a satellite navigation system, or if you are lost and trying to locate yourself on an old fashioned map. Most navigation systems only support Latitude/Longitude format which can be difficult to use, by converting to national grid it makes the process easier with most maps showing the national grid scale along the axis, a must for the avid walker.

Conversion is simple, enter your latitude/longitude or national grid reference, hit calculate and your done. The conversion process uses the OSTN02* database consisting of over 300'000 weypoints, to provide accurate results. No network connectivity is required for the conversion so this can be used in the most isolated of locations.

Alternatively select the current location tab and within seconds you location will be displayed in both formats including an estimated altitude (iPhone 3G required for altitude data).

It is possible to customise the number of digits used for the national grid reference and the following latitude/longitude formats are supported:-

  1. DDMMSS (56°32'07)
  2. DDMM.MM (56°32.11667)
  3. DD.DDDD (56.5352778°)

For more information on the National Grid Reference system for Great Britain take a look at the Ordinance Survey guide


This application only supports the National Grid Reference for Great Britain and therefore positions outside this area cannot be converted to a grid code. However it is still possible to use the current location screen to display your latitude/longitude and altitude.

Location information may not always be available and will require network connectivity on 1st generation iPhone's and iPod Touch's.

* This software is using the OSTN02 transformation, this is Crown copyright 2002. All rights reserved.