MGRS Precision Calculator
The Military Grid Reference System (MGRS) names a position with a grid zone, a 100 km square identifier, and then a numeric easting and northing. The number of digits you quote sets how precisely the box is located: one digit per axis resolves to 10 km, five digits per axis resolves to 1 m. This calculator converts the number of digits into a ground resolution (the side length of the named box) and the area of that box, so you can pick the right precision for your task or read the precision of a reference you have been given.
MGRS precision formula
resolution (m) = 10^(5 - digits)
total figures = 2 * digits
box area (sq m) = resolution^2
box area (hectares) = resolution^2 / 10000
digits is the count of digits used for each of easting and northing (1 to 5). Five digits per axis is the maximum MGRS precision and resolves to 1 metre. The box area is the square of the side length.
MGRS precision context
- 1 digit per axis (2 figures): 10 km resolution.
- 2 digits per axis (4 figures): 1 km resolution.
- 3 digits per axis (6 figures): 100 m resolution.
- 4 digits per axis (8 figures): 10 m resolution.
- 5 digits per axis (10 figures): 1 m resolution, the MGRS maximum.
MGRS precision: frequently asked questions
How does MGRS precision relate to the number of digits?
A Military Grid Reference System (MGRS) reference quotes equal numbers of easting and northing digits. The ground resolution is 10^(5 minus n) metres, where n is the number of digits in each of easting and northing. So 5 digits gives 1 m, 4 gives 10 m, 3 gives 100 m, 2 gives 1 km, and 1 gives 10 km.
What is a full-precision MGRS reference?
Full precision is 5 digits of easting and 5 of northing (10 figures total after the 100 km grid square), giving 1-metre resolution. The reference looks like 18TWL8040011600 where 18T is the grid zone, WL the 100 km square, then 80400 easting and 11600 northing.
Why do easting and northing use the same number of digits?
MGRS always pairs equal-length easting and northing strings so the reference can be split unambiguously down the middle. A 10-figure reference is 5 plus 5; an 8-figure reference is 4 plus 4 at 10 m resolution.
What does the ground resolution actually mean?
It is the side length of the smallest grid square the reference can name. At 100 m resolution (3 plus 3 digits) the reference identifies a 100 m by 100 m box; the true position is somewhere inside that box. More digits shrink the box.
How large an area does each precision cover?
The area is the square of the resolution: 1 m gives 1 square metre, 10 m gives 100 square metres, 100 m gives 1 hectare (10,000 square metres), and 1 km gives 1 square kilometre. This calculator reports both the side length and the box area.
Official sources
- U.S. National Geospatial-Intelligence Agency: MGRS and coordinate systems.
- U.S. Geological Survey: grid reference systems.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.