FIELD REFERENCE / UPDATED 7 SEPTEMBER 2026
MGRS coordinates.
Read the grid.
MGRS means Military Grid Reference System. It expresses a location with a grid zone, a lettered square and paired easting/northing digits. It is based on UTM and, at the poles, UPS. NGA coordinate-system reference.
Read right, then up
Worked example: 18T WL 85372 11523. Spaces make the parts easier to read.
- Find grid zone
18Tand squareWLon the matching map. - Read the first numeric half east:
85372, or 85,372 meters within that square. - Read the second half north:
11523, or 11,523 meters.
Keep the two numeric halves the same length. FGDC's grid-reading guide explains this easting-first method.
More digits mean a smaller square
| Numeric digits | Same example | Square size |
|---|---|---|
| 4 (2 + 2) | 18T WL 85 11 | 1 km × 1 km |
| 6 (3 + 3) | 18T WL 853 115 | 100 m × 100 m |
| 8 (4 + 4) | 18T WL 8537 1152 | 10 m × 10 m |
| 10 (5 + 5) | 18T WL 85372 11523 | 1 m × 1 m |
To shorten a grid, remove digits from the end of each numeric half. Do not round into the neighboring square.
Precision is not GPS accuracy. Ten digits identify a one-meter square; they do not prove your phone knows its position within one meter. Buildings, trees, satellite geometry and receiver quality affect the fix. GPS.gov explains these limits.
MGRS, UTM and latitude/longitude
Latitude and longitude describe angles. UTM uses a zone and meter-based coordinates; MGRS encodes grid locations with square letters and shorter numeric pairs. USNG is closely related, but datum conventions matter when exchanging or converting old coordinates.
Use the free MGRS coordinate converter for WGS84 MGRS, UTM and latitude/longitude. Calculations run in your browser. Keep the full zone and square letters when the receiving person or tool has no shared map context.
Before using a coordinate in the field
- Confirm the map datum and coordinate format.
- Check the reported GPS accuracy and age of the fix.
- Match easting/northing lengths and read the complete coordinate back.
- Verify that the maps you need are available offline; carry an independent navigation reference.
Common MGRS questions
What does MGRS stand for?
Military Grid Reference System. It expresses a location using letters and numbers based on the UTM and UPS grid systems.
How many digits are in an MGRS coordinate?
The numeric location normally contains an even number of digits: half easting, half northing. A 10-digit grid has five of each, in addition to its grid zone and square letters.
Does a 10-digit grid mean my GPS is accurate to one meter?
No. It identifies a 1 m by 1 m grid square. The position estimate can be less accurate because of the receiver, signal conditions and surroundings.
Can I convert MGRS to latitude and longitude?
Yes. Use a converter and match the datum used by the original coordinate. The Red Grid web converter uses WGS84 and performs calculations in your browser.
Can I use MGRS without cell service?
The coordinate format does not depend on a network. A phone with a usable satellite fix can show MGRS without cell service. Map imagery must already be available locally for offline viewing.
Put your grid on your phone
Red Grid MGRS displays a 10-digit grid with a usable phone location fix. The free core also includes a waypoint, bearing and distance. Compare the app's Free and Pro features.