Military Grid Reference System (MGRS) Explained

If you've seen a coordinate string like 31UDQ4825111943 and had no idea what to make of it, you've encountered MGRS — the Military Grid Reference System. It's the standard used by NATO forces for all ground navigation, artillery fire missions, close air support coordination, and search and rescue.

Structure of an MGRS Coordinate

An MGRS reference like 31UDQ4825111943 breaks down as follows:

• 31U — the UTM grid zone (zone 31, band U)
• DQ — the 100,000-metre square designator within the zone
• 48251 — easting within the 100 km square (to 1 metre precision)
• 11943 — northing within the 100 km square (to 1 metre precision)

MGRS is built on top of UTM, with the grid zone system carried over directly. The 100 km square letters are the key difference — they eliminate the need to write large UTM easting/northing numbers.

Precision Levels

MGRS coordinates can be expressed at different precision levels by using fewer digits:

• 6 digits (e.g., 31UDQ482119) — 100 metre precision
• 8 digits — 10 metre precision
• 10 digits — 1 metre precision

In field use, 6-digit MGRS is common for general navigation; 10-digit for precise targeting.

Who Uses MGRS Beyond the Military?

MGRS has spread beyond active-duty use into adjacent fields:

• Search and rescue teams often use MGRS when coordinating with military assets
• Wildfire incident commanders use MGRS for resource deployment
• Contractors on military bases frequently deal with MGRS for location reporting
• Outdoor enthusiasts who served in the military often prefer MGRS for backcountry navigation

Converting MGRS

Use our MGRS to Decimal Degrees converter to translate MGRS references to standard lat/long, or our full converter to see any MGRS coordinate in all seven formats simultaneously. For more context on how the military uses coordinates, see our military coordinates guide.