Tables of MGRS/USNG Grid Letters

Introduction

The tables of MGRS grid letters that I have found on the Web are incomplete and all but illegible (see References). I have therefore produced some tables of my own. Note that these tables agree with the USNG grid letters wherever the latter are defined.

There are two sets of tables:

a set in the form of MGRS "maps" that cover areas of particular interest to me: although of limited scope they are easier to read, and contain more information, than the general purpose tables described below. Although these maps are (just) legible on-screen, they are intended for printing.
a set of eight general-purpose MGRS tables covering the whole UTM globe. These tables can be viewed on-screen or printed - when printed each table occupies one sheet of A4.

Non-standard Zones

Neither set makes allowance for the "Non-standard" zones covering Norway and Svalbard. For information on these zones see References.

The Maps

So far I have produced just three maps, covering the following areas:

	144°W to 96°W	96°W to 48°W	12°W to 36°E
35°N to 60°N	North-West USA and Canada	North-East USA and Canada	Europe

Similar maps covering other areas could be produced on request.

Each "map" is a Lambert Conformal Conic Projection (see References) of the relevant area:

Latitude and Longitude are printed in red.
Zone numbers are printed in black along the bottom. Zone 18 for example extends from 78°W to 72°W.
Zone Designation Letters are printed in black along the left-hand side.
The first two digits of the 7-digit UTM Eastings and Northings are printed along the bottom and right-hand side respectively. Note that the first digit of the Easting is always zero.

Not all the incomplete squares on zone boundaries - the "seam squares" - have letters printed in them, because of lack of space. The missing letters can easily be extrapolated (remembering that the letters I and O are never used). For example the four seam 'squares' closest to the point 18.001°E 36°N are YA, BF, YV, BE. This point is just in zone 34, and is therefore in square 34SBE. It actually has UTM coordinates Zone 34 0229668m E 3988109m N, so the full 1m MGRS reference for this point is 34SBE2966888109, usually shortened to BE2966888109.

Similarly the point at 17.999°E 36°N is just in Zone 33, and is therefore in square 33SYV. It has coordinates Zone 33 0770331m E 3988109m N, so its full MGRS reference is 33SYV7033188109.

The Base Map is Missing...

It was intended that each map should be printed over an outline base map of the relevant area. Unfortunately, appropriate base maps were not available at the time of publishing. I hope to produce updated versions in due course: Mail me for a progress report.

Alignment of Grid Squares

Note that, except at the centre of each zone, the edges of the grid squares do not line up with lines of latitude or longitude. The maps correctly indicate, if only approximately, the magnitude of the discrepancy.

For example, the point 56°N 15°E has the MGRS coordinates 33VWC0000006079 and it can be seen from the map that this point does indeed lie just above the SW corner of square WC. The square XC immediately to the East is a seam square, and the edge of the zone at 56°N 18°E lies just inside this square at 33VXC8707110141. It can be seen from the map not only that this point is indeed just inside square XC, but that its northing is slightly greater than that of the previous point mentioned - the actual difference, just over 4km, counts as "slight" in this context.

Printing The Maps

Although these maps are (just) legible on-screen, they are intended for printing.

To get the best results:

choose the smallest available text size (under the View menu in IE5). This will prevent the page titles taking up too much of the picture area.
Make sure the printing margins are set appropriately. Using IE5 and an Epson printer I have found left and right margins of 15mm and top and bottom margins of 20mm to be satisfactory. When printing, the table is set to use all the available page height; if the map will not fit on one page, decrease the left and right margins in small increments or increase the top and bottom margins until it does.
The maps were prepared at high resolution: for best results set your printer to at least 360dpi. 720dpi or more may produce even better results.
If you have the technology, printing the raw .gif images from a graphics program may give ultimate quality. The images are created to fit nicely on an A4 page with 360dpi resolution.

The Tables

The pattern of MGRS Grid letters recurs every 6 zones. For any given latitude therefore only two tables are required: one covering Zones 1,2,3 and thus also Zones 7,8,9, 13,14,15 and so on, the other covering Zones 4,5,6, and thus Zones 10,11,12, 16,17,18, etc. However, each table only spans about one quarter of the overall latitude range, so that eight tables required in total:

For Northings in the range...	Approx Latitude Range	Zones
For Northings in the range...	Approx Latitude Range	1,2,3, 7,8,9,...	4,5,6, 10,11,12,...
Northern Hemisphere above 4700km N	42°-86°N	Table 1	Table 2
Northern Hemisphere, equator to 4700km N	0°-42°N	Table 3	Table 4
Southern Hemisphere, equator to 4700km S	42°S-0°	Table 5	Table 6
Southern Hemisphere below 4700km S	80°S-42°S	Table 7	Table 8

Part of a typical table should look like this:

If a table does not display on-screen as above, increase the size of your Browser Window or decrease your Browser's Text Size.

For each 100km grid square, specified by first two digits of its 7-digit UTM Easting and Northing, the Zone Designation Letter and MGRS square letters are given by the tables. A latitude range for the squares is also given - this is strictly correct only for the centre of each zone (ie the E side of the "04" squares and the W side of the "05" squares), but the error is always quite small, as can be seen from the "maps" described previously - see Alignment of Grid Squares above.

Because the meridians get closer and therefore the actual Zones get narrower near the poles, not all the 100km squares listed in the tables can appear in valid MGRS references. Squares shown in black are completely inside the zone, but squares shown in red are incomplete "seam squares" which lie on a zone boundary. Squares shown in grey should not appear in valid MGRS references at all.

As an example, consider again the point 18.001°E 36°N. From Table 4 (part shown above), first subtable (Zone 4 etc) it can be seen that Longitude 18.001°W is just in zone 34 (18°-24°E). The grid square BE whose south-west corner is at 0200000m E 3900000m N covers the approximate latitude range 35.23°-36.13°N, and being printed in red covers the western edge of the zone. The zone Designation letter is S. The 100km MGRS reference is therefore 34SBE.

Similarly the point at 17.999°E 36°N is just in Zone 33 (12°-18°E), to be found on Table 3, third subtable (Zone 3 etc). This point is therefore in square 33SYV.

Printing The Tables

To print each table on one page of A4 you will probably need to reduce the printing margins in your Browser. You may also need to set your browser's text size (under the view menu in IE5) to a smaller size. Using IE5 and an Epson printer I have found "medium" text size, left, right and bottom margins of 18mm and a top margin of 12mm to be satisfactory.

References

Alternative Tables

See for example:

Reference	See	Comments
Defense Mapping Agency pub. DMA 8358.1: Datums, Ellipsoids, Grids, and Grid Reference Systems	UTM Zones (Map)	The map is incomplete and all but illegible.
Dana (Cordinate system overview)	UTM Zones (Map)	a copy of part of the above?
ATLAS FLORAE EUROPAEAE	MGRS table	does not include the Zone Designation Letter or lat/lon information.

Lambert Conical Conformal Projection

A standard map projection, see eg:

DMA 8358.1 as above	2-5 PROJECTIONS: section 2-5.7
Dana as above	Conic Projections

Non-standard Zones

See for example the ATLAS FLORAE EUROPAEAE quoted above, which contains a map of these zones.

Revised 2003-09-21

Uprated to xhtml 2005-08-16