Gridmark

Free tool

MGRS, USNG, UTM and lat/long converter

Type any one format and see the others. It runs entirely in your browser, and nothing you enter is sent anywhere.

What you can enter

  • MGRS or USNG: 17RMM6350157423 or 17R MM 63501 57423. Shorter grids such as 17R MM 635 574 work too.
  • UTM: zone, N or S for the hemisphere, easting, northing, such as 17N 463501 3157423.
  • Latitude and longitude: decimal degrees, such as 28.5431, -81.3731 or 28.5431 N 81.3731 W.

How the results work

  • All values use the WGS84 datum. If your paper map uses another datum, such as NAD27, the same place has different numbers.
  • Grids are shown to one meter and truncated, not rounded, because a grid names the square a point falls in.
  • A shorter grid names a larger square, so it converts from that square's center.
  • It covers 80°S to 84°N, including the Norway and Svalbard zone exceptions. The polar regions use a different grid (UPS), which this page doesn't convert.

We checked the calculations against 20,000 points computed with GeographicLib, and every grid matched. Treat the results as a navigation aid, not for surveying or anything where an error could cause harm.

Need this in the field?

Gridmark does these conversions offline on iPhone, iPad and Apple Watch, along with routes, tracks and offline maps. New to grids? Start with how to read an MGRS grid.