Reading an MGRS coordinate seems tricky, but it follows a fixed order: from large square to small square, and within that square first right and then up. Take 31U ET 12345 67890 as an example.
Step 1 — The Grid Zone Designator
The first part, 31U, is the Grid Zone Designator. The 31 is the UTM zone (a vertical strip of 6° longitude) and the U is the latitude band (a horizontal strip of 8° height). Together they mark out a large square on earth within which the rest of the coordinate applies.
Step 2 — The 100 km square
The two letters ET identify a 100 × 100 km square within the grid zone. The first letter runs in the east-west direction (easting), the second in the north-south direction (northing). That way you know which 100 km square you are in.
Step 3 — Reading easting and northing ("read right up")
Split the digits into two equal halves: the first half is the easting (distance to the right, east), the second half the northing (distance upward, north). In 12345 67890 the easting is 12345 and the northing is 67890. Remember the rule of thumb "read right, then up": first to the right, then up.
Step 4 — The number of digits determines the precision
The more digits, the more precise the position:
| Digits | Example | Accuracy |
|---|---|---|
| 2 (1+1) | 31U ET 1 6 | 10 km |
| 4 (2+2) | 31U ET 12 67 | 1 km |
| 6 (3+3) | 31U ET 123 678 | 100 m |
| 8 (4+4) | 31U ET 1234 6789 | 10 m |
| 10 (5+5) | 31U ET 12345 67890 | 1 m |
Automatic reading with MilMap
In MilMap you don't have to count or split: you type or paste the MGRS code and the app drops a marker on the map straight away. The other way around, MilMap shows the MGRS coordinate for every point, so you can read it right off the screen and pass it on.