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Spreadsheet for coordinate calculations

Our coordinate calculations spreadsheet enables you to carry out common calculations with coordinates. It includes a full set of Transverse Mercator projection functions. Calculations include:

  • Project latitude and longitude to grid eastings and northings for any Transverse Mercator map projection, including the Ordnance Survey National Grid – and vice versa.
  • Compute local scale factor and grid convergence at any point on the grid, and compute t-T and true azimuth between any pair of points on the grid.
  • Convert latitude and longitude coordinates to cartesian XYZ coordinates and vice versa.
  • Perform simple ("Helmert" style) coordinate transformations. E.g. between WGS84 and OSGB36 with an accuracy of about 3 metres.
  • Reformat latitude and longitude coordinates between:
    • Degrees, Minutes & Seconds;
    • decimal Degrees; and
    • Degrees & Decimal Minute formats.

"A guide to coordinate systems in Great Britain" (linked to in the box opposite) acts as the user manual for some of the calculations you can perform using the spreadsheet (scale factors, convergence and t-T are included in the spreadsheet but not in the guide).
In particular it explains the limitations of the type of datum transformation included in the spreadsheet, which you should bear in mind. If you need transformation accuracy better than the 3 metres, you should use OSTN15 and OSGM15 instead of the simple transformation in the spreadsheet.

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© Ordnance Survey 2019