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Tips and questions relating to the GPS modules from SFE
By rxbandit
#63351
Does anyone have any concise examples or code converting from UTM coordinate system to Lat/Long and vice versa? I haven't been able to find a good example or algorithm for this.
By JimEli
#64353
...
By fll-freak
#119088
The gold standard for UTM/UPS to MGRS/UPS to Lat/Lon using user selected datum and ellipsoid is GEOTRANS created and published by the USA government. This is THE library to use for accurate conversions.

The library can be hacked to include just what you want. If you don't care about MGRS then you can exclude that module. Code is free an available with a quick google of "GEOTRANS download"