MGRS grid

Military Grid Reference System, built on UTM. Square cells whose identifier length sets precision (100 km → 1 m). Widely used for surveying and defence.

The interactive explorer below is rendered with deck.gl and behaves like the h3geo.org map: the MGRS precision follows the zoom and cells are generated in the browser for whatever is in view. Two neighbouring precisions are shown at once — the current level with a darker, heavier border and the next finer level with a lighter, thinner one. The cell references come from mgrs and the per-zone UTM squares from proj4js, reproducing the exact M3S maths so the references and edges match m3s.mgrs. MGRS only refines down to 100 km, so it has no whole-globe level — zoom out and the explorer asks you to zoom back in. GIS-native (lon, lat) order is used throughout.

Why MGRS?

MGRS is for coordinates that humans read in the field: it is the NATO standard on printed maps, GPS units and surveying gear, and because cells are true metres in UTM, 31UDQ48 narrows down to a square you can pace out on the ground. Use it when interoperating with defence, search-and-rescue or surveying workflows. It is a poor analysis grid, though: cells do not tile seamlessly across UTM zone boundaries and there is no single global hierarchy. For coarse spoken area reference use GARS grid; for worldwide analysis grids see EA-Quad grid or S2 grid.

Usage

Encode a point and tile a small bounding box around Paris — same result in Python and JavaScript (both call the shared core):

Python

import m3s

cell = m3s.MGRS.from_geometry((2.35, 48.86))            # (lon, lat)
cells = m3s.MGRS.from_geometry((2.2, 48.8, 2.4, 48.9))  # bbox
print(cell.id, len(cells))

JavaScript

import * as m3s from "m3s";
await m3s.ready();

const cell = m3s.MGRS.fromPoint(2.35, 48.86);            // (lon, lat)
const cells = m3s.MGRS.fromBbox([2.2, 48.8, 2.4, 48.9]); // bbox
console.log(cell.id, cells.length);

from _deckmap import DeckExplorer, read_grid_js


DeckExplorer(
    center=(2.35, 48.85),
    zoom=7,
    grid_js=read_grid_js("mgrs"),
    hover="#332288",
    wasm=True,
)