Sooner or later you have to convert MGRS coordinates: to latitude and longitude to share with an ordinary map app, or to UTM for GIS work. And the other way around. Here you read how conversion works and how to carry it out reliably.
Which conversions are there?
- MGRS ↔ latitude/longitude (WGS84) — the most requested, to swap with GPS apps, Google Maps and pilots.
- MGRS ↔ UTM — simple, because they share the same projection; especially relevant for GIS and surveying.
- Adjusting precision — shortening a 10-digit code to 6 digits, or the other way around, is also part of "converting".
How a conversion works
Under the hood, every conversion goes via UTM: MGRS is first translated to full UTM easting/northing, and those are converted to degrees using the UTM formulas on the WGS84 ellipsoid — or vice versa. With the letters of the 100 km square and the zone boundaries you have to be precise; that is where manual calculations most often go wrong.
Standalone converter or map app?
An online converter gives you one answer for one coordinate. Handy for a quick check, but in practice you usually want to see the converted position on a map, in context with your route, waypoints and terrain. A map app does the conversion and shows the result in the right place.
Convert and use in MilMap
In MilMap you enter a coordinate — MGRS, UTM or lat/long — and see it directly on the map with all formats side by side. You set the display format per map, share points with anyone who uses a different system, and export route books with MGRS for each point. That way converting is no longer a separate step but part of your work.
Convert and use MGRS in MilMap — free to try.