North Pinnacle

Sheet 5 · Grid references

What does this grid reference mean?

Paste an MGRS or UTM reference, or a latitude and longitude, and every part of the grid reference is taken apart and explained.

MGRS (31U DQ 48251 11932, spaces optional), UTM (31 N 448251 5411932) or degrees.

Try:

Breakdown

31U DQ 48251 11932

  1. 31 UTM zone

    Zone 31 is a 6° strip of longitude from 0° to 6°E. Its central meridian, 3°E, is given the easting 500,000 m, so eastings never go negative.

  2. U Latitude band

    Band U covers 48°N to 56°N. Bands are 8° tall and lettered C to X from south to north, skipping I and O; N is the first band north of the equator, so this point is in the northern hemisphere.

  3. D 100 km column

    Column D is the 4th letter of this zone's set (ABCDEFGH), so the square starts 400,000 m east of the zone's false origin. Zones cycle through three sets of column letters.

  4. Q 100 km row

    Row letters repeat every 2,000 km of northing. Q is position 15 in this zone's sequence (ABCDE…, starting at A because zone 31 is odd), and the band letter says which 2,000 km block applies: the square's south edge is at northing 5,400,000 m.

  5. 48251 Easting within the square

    48,251 m east of the square's west edge, written with 5 digits.

  6. 11932 Northing within the square

    11,932 m north of its south edge. Easting always comes first: "read right, then up".

With 5 digits per coordinate the reference names a 1 m square, and the point lies somewhere inside it: MGRS truncates, it does not round.

0°Equator
Zone 31, band U among the 60 zones and 20 bands
DQ 0100 km E 0100 km N
Inside square DQ: 10 km grid lines and the 1 m square

Same point, every precision

DigitsReferenceSquare
031U DQ100 km
131U DQ 4 110 km
231U DQ 48 111 km
331U DQ 482 119100 m
431U DQ 4825 119310 m
531U DQ 48251 119321 m
UTM
31 N 448251 5411932
Latitude, longitude
48.858198, 2.294496

Reading a grid reference

An MGRS reference has three parts. The grid zone designator (31U) names a cell of the UTM grid: one of 60 zones, each 6° of longitude, and one of 20 latitude bands lettered C to X. The 100 km square identifier (DQ) is a column letter and a row letter. The numerical location (48251 11932) gives the easting and then the northing inside that square, always as two halves of equal length.

The number of digits sets the precision: one digit each pins a 10 km square, two a 1 km square, three 100 m (the familiar six-figure reference), four 10 m and five 1 m. References are truncated, so the point lies inside the square named and never in a neighbouring one. Read the digits "right, then up": easting first.

UTM writes the same position in full metres: zone, hemisphere, easting and northing. The letters in MGRS are only a shorthand for the hundreds-of-kilometres digits. Two places break the regular grid: zone 32V is widened to cover south-west Norway, and zones 31X to 37X over Svalbard are 9° or 12° wide, with 32X, 34X and 36X left out.

Sources

Questions

What is the difference between UTM and MGRS?

None in position: MGRS is UTM with the leading digits of easting and northing replaced by two letters, which makes references shorter and easier to read out over a radio.

Can I enter a British or Irish national grid reference?

No. Those grids look similar (SU 12345 67890) but use different projections and datums. Convert them to latitude and longitude with a national mapping agency's tool first.

Why does the square letter change when I move a few metres?

You crossed a 100 km grid line. The letters change and the digits restart from 00000; the two references are still only metres apart.