Coordinate conversion

OSTN15/OSGM15, ETRS89 to OSGB36 and British National Grid tools. 3 tools, in our suggested starting order (how we order).

ordnancesurvey.co.uk

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Cost not checked

Ordnance Survey's coordinate transformation tools and resources (ETRS89, OSGB36, OSTN15/OSGM15).

Best for Anyone converting GNSS coordinates to British National Grid.

UK-specific

Cost Not checked.

Source · checked 15 Oct 2026

proj.org

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Free (verified)

Open-source library and command-line tools for coordinate transformations.

Best for Developers and GIS users automating conversions.

Open source

Cost Open source, X/MIT licence (stated on site).

Source · checked 15 Oct 2026

epsg.io

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Cost not checked

Reference page for OSGB36 / British National Grid definitions.

Best for Anyone setting up BNG in software.

Cost Not checked.

Source · checked 15 Oct 2026

Know a tool we've missed?

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