Co-ordinate Converter
Version History
Software Version (currently unavailable)
Version 1.2 - November 2007
  • Introduced support for County Series sheet co-ordinates (Great Britain & Isle of Man only).
  • Allowed for input of numerical National Grid square codes.
  • Improved accuracy of National Yard Grid transformations.
  • Program now remembers the result of the last co-ordinate transformation on start-up.
Version 1.1 - October 2006
  • Introduced support for GB National Yard Grid.
  • Introduced support for County Series co-ordinates (Great Britain & Isle of Man only).
  • Grid square codes no longer case-sensitive.
  • Minor improvements and 'tidying up' in the appearance and operation of the program.
Version 1.0 - September 2004
  • Improved algorithm for conversion between Transverse Mercator grids and Geodetic co-ordinates.
  • Increased level of accuracy in co-ordinate transformations.
  • Expanded support of Cassini (Delamere) co-ordinates to include Scotland (!).
  • Introduced support for War Office Cassini Grid co-ordinates.
  • Introduced support for Bonne co-ordinates (Scotland).
  • Introduced support for conversions between Irish National Grid and OS Ireland Geodetic co-ordinates.
Version 0.9 beta - July 2004
  • First release of program.
  • Support for 3-way conversion between the following projected co-ordinate systems:
    • Cassini (Delamere) co-ordinates
    • GB National Grid
    • Latitude/Longitude (OSGB36)
Web Version
Version 1.2.003 - 4 May 2009
  • Revised conversion methods for Cassini and Bonne projection systems with improved accuracy.
  • Slightly altered OSTN02 initialisation code to minimise creation of global variables.
Version 1.2.002 - 20 April 2009
  • Revised algorithms for conversion to/from Transverse Mercator co-ordinate systems with improved accuracy.
  • Added support for conversions to/from UTM Zone 29, 30 and 31 co-ordinates in both ETRS89 and ED50 datums.
  • Added support for conversions to/from geodetic co-ordinates in ED50 datum for GB & Ireland.
  • Expanded supported range of 'Great Britain' area co-ordinate transformations to include Channel Islands.
  • Co-ordinate Converter can now be used as an API (see main page for details).
Version 1.2.001 - 2 April 2009
  • Added support for conversion to/from County Series co-ordinates and sheet references for Great Britain and the Isle of Man.
  • Split Great Britain and Ireland conversion sections to separate pages.
Version 1.1 beta (build 009) - 16 February 2009
  • Slightly improved accuracy of conversions to/from Great Britain area ETRS89 (GPS-compatible) latitude/longitude.
Version 1.1 beta (build 008) - 9 February 2009
  • Added support for conversion to/from Irish Transverse Mercator Grid, War Office Irish Grid and Bonne Projection (Ireland) co-ordinates.
  • Fixed unit scaling error concerning War Office Cassini Grid transformations.
Version 1.1 beta (build 007a) - 8 February 2009
  • Streamlined and re-organised some code to allow slightly faster operation of transformations.
Version 1.1 beta (build 006) - 5 February 2009
  • Added support for Ireland area conversion to and from ETRS89 Latitude/Longitude (GPS-compatible).
  • Improved accuracy of conversion to/from ETRS89 Latitude/Longitude.
  • Improved out-of-range handling of conversion to/from ETRS89 Latitude/Longitude.
Version 1.1 beta (build 005) - January 2009
  • Improved page layout.
  • Improved error-handling of conversion to/from ETRS89 Latitude/Longitude.
Version 1.1 beta (build 004) - January 2009
  • Added provisional support for Great Britain area conversion to and from ETRS89 Latitude/Longitude (GPS-compatible).
Version 1.1 beta (build 003) - December 2008
  • First release of web-based version.
  • Support for conversion between the following projected co-ordinate systems:
    • Latitude/Longitude (OSGB36)
    • GB National Grid
    • GB National Yard Grid
    • Cassini (Delamere) co-ordinates
    • War Office Cassini Grid co-ordinates
    • Bonne co-ordinates (Scotland)
    • Latitude/Longitude (OS Ireland 65)
    • Irish National Grid
Legal notice

Co-ordinate Converter is copyright © 2004-2009 Ed Fielden.
You may use Co-ordinate Converter for non-commercial use only, except by prior agreement.
While great care has been taken in development and testing, the results of transformations provided by Co-ordinate Converter should not be relied upon for critical applications. No liability can be accepted for any loss or damage - direct or consequential - arising from the use of Co-ordinate Converter.

Page last updated: 24 April 2012