This utility converts a British or Irish grid reference into Latitude and Longitude. It is believed to be accurate to within 5 metres, but there is no guarantee. Use at your own risk.
You can enter a grid reference:
This utility will be withdrawn at the end of 2014, unless it breaks before then, because I'm not willing to chase after the shifting sands of PHP in order to maintain it. The source code is not and will not be available.
My home page.