Our coordinate calculations spreadsheet enables you to carry out common calculations with coordinates. It includes a full set of Transverse Mercator projection functions, which allows you to:
- Convert 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 at any point on the grid, and computer grid convergence, 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.
- Convert latitude and longitude coordinates in any coordinate system to any other coordinate system. For instance, GPS coordinates may be converted to Ordnance Survey National Grid coordinates for anywhere in Great Britain with an accuracy of about 5 metres.
- Reformat latitude and longitude coordinates between:
- Degrees, Minutes & Seconds;
- decimal Degrees; and
- Degrees & Decimal Minute formats.
The document opposite is the user manual for the calculations you can perform using the spreadsheet. It explain the limitations of this type of datum transformation, which you should bear in mind.
For example, if you need accuracy greater than the nearest 5 metres, you should use OSTN02 and OSGM02 on the surveying guidance page, rather than the simple conversion GPS to National Grid conversion requiring better than 5-metre accuracy, you should not use the simple transformation calculated by the spreadsheet.
Note: Projection functions such as scale factors, convergence and t-T are included in the spreadsheet but not in the guide.