Want to share an MGRS coordinate with someone who works in latitude and longitude — for example an ordinary GPS app, Google Maps or a pilot? Then you convert MGRS to WGS84 decimal degrees. The principle is always the same.
How the conversion works
MGRS sits "on top of" UTM, so the conversion to latitude and longitude happens in two steps:
- MGRS → UTM. From the grid zone and the two square letters you derive the full UTM easting and northing (in meters), together with the zone and the hemisphere.
- UTM → latitude/longitude. Using the standard UTM formulas (on the WGS84 ellipsoid) you convert that easting/northing into decimal degrees.
The result is a coordinate like 52.3676, 4.9041 that you can paste into virtually any map or navigation app.
Mind the precision
An MGRS coordinate with few digits refers to a larger square. When you convert such a coordinate, you usually get the center (or the corner) of that square. If you want meter-level accuracy, use a 10-digit MGRS coordinate.
Calculating by hand is error-prone
The UTM formulas contain several series expansions; doing them by hand takes time and quickly produces rounding errors. In practice you let software do this.
Automatic conversion in MilMap
MilMap converts MGRS to latitude and longitude (and back) in real time. Place a point with an MGRS code and you instantly see the same location as lat/long — ready to share with anyone using a different system. That way you never have to calculate by hand again.
Convert MGRS to GPS in MilMap — free to try.