Grid Reference UK - OSGB36

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About this app

Version 2 is now here! 🥳 It contains a lot of new features requested by the users and a whole new look with the sleek Material 3 Design.

Transform your GPS (WGS84 coordinates) 🛰️ into British National Grid Reference and OSGB36 coordinates.

Accurate and reliable, UK Grid Tools works both online and offline. And the best part: it is completely FREE🤩 !

👉Manual input of coordinates (Latitude & Longitude, Easting & Northing or British National Grid Reference)
👉Show GPS coordinates (WGS84/ETRS89 coordinates)
👉Show OSGB36(15) coordinates accurate to the metre
👉Show British National Grid Reference for your position ❤️. Customisable values:
➡️set the number of figures to display. From no figures (e.g. SV to full 10 figures e.g. SV 95461 36567
➡️set the separator between elements of the grid reference to either: none, space, dash or underscore
👉Dark or light theme depending on your preference. Or simply use the System default theme
👉Customisable format for GPS coordinates. You can:
➡️display degrees as either Decimal Degrees (D°), Degrees and Minutes (D°M') or Degrees, Minutes and Seconds (D°M'S")
➡️show quadrant letters (E/N/S/W), signs (+/-) or none
➡️set the decimal places on your degree format
👉Easily share your current location 🤝
👉Open the location in your favourite map app 🗺️
👉 See the device's reported accuracy when using GPS readings
👉Tap and hold on any of the values to copy them to clipboard

All similar apps out there that are geared towards transforming WGS84 coordinates into British National Grid Reference or OSGB36 coordinates do not perform accurate conversions 😭. Extensive testing has shown us that most of them use a Helmert 7-parameter datum transformation which, whilst good for general location purposes, the results in these apps do not offer high enough accuracy.

According to Ordnance Survey, for the transformation from ETRS89 (by all intents and purposes it is the same as WGS84 within the UK) to OSGB36 in Britain, using a single Helmert transformation will give errors of up to 3m (95%) in plan and 3.5m (95%) plan and height 😲, depending where in the country the points of interest are. In our tests we have seen errors as high as 10m in other apps.

This has led us to develop our own solution which provides accurate transformations between WGS84 (ETRS89) and OSGB36. This allows us to produce British Grid Reference values to the full 10 figures. Our results match all the test coordinates offered by Ordnance Survey.

In order to achieve the most accurate results, we use the OS provided OSTN15 transformation model applied to approximate coordinates. More details on the algorithm and accuracy can be found in the official document from Ordnance Survey titled "A Guide to Coordinate Systems in Great Britain".

Because we want to keep the app size small, we implement the 20km grid model. This offers you horizontal accuracy of less than 0.150m in 95% of cases. With this in mind, our Grid Reference App will provide you true British National Grid Reference values up to 10 figures and OSGB36(15) coordinates accurate to the metre.
Updated on
Jan 11, 2024

Data safety

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What's new

Small bug fixes.