Different tools, maps, and receivers speak different coordinate dialects: a smartphone gives you decimal degrees, a marine chart prefers DDM (degrees decimal minutes), a land survey uses UTM, a military map uses MGRS, and a spatial database might index by Geohash. This formatter takes one WGS84 latitude and longitude and renders it in all of them at once, so you never have to run separate conversions or remember which formula applies to which system.
The formats explained
| Format | Example | Typical use |
|---|---|---|
| Decimal degrees (DD) | 51.4778° N, 0.0014° W | GPS, web mapping, APIs |
| Degrees-minutes-seconds (DMS) | 51° 28’ 40” N | Traditional paper maps, aviation charts |
| Degrees decimal minutes (DDM) | 51° 28.666’ N | Marine navigation, some handheld GPS units |
| UTM | 30U 699311E 5710154N | Land surveying, GIS software |
| MGRS | 30UXC9931110154 | Military, search and rescue, hiking |
| Geohash | gcpuuz… | Spatial database indexing, proximity search |
How each conversion is computed
DD, DMS, DDM are pure arithmetic. To go from decimal degrees to DMS: the integer part is degrees; multiply the fractional part by 60 to get minutes; multiply the fractional minutes by 60 again to get seconds. DDM stops at minutes, leaving them as a decimal rather than converting further to seconds.
UTM is a real cartographic projection. The tool applies the standard Transverse Mercator series expansion on the WGS84 ellipsoid, determines the 6-degree longitude zone automatically, selects the latitude band letter (C through X), and outputs easting and northing in metres. A correctly formatted UTM coordinate always includes the zone number, hemisphere indicator or band letter, easting, and northing — for example 30U 699311E 5710154N.
MGRS is built on top of UTM. It adds a two-letter 100,000-metre square identifier specific to the UTM zone, then appends a numeric easting and northing within that square at the desired precision. A 10-digit MGRS string locates a point to 1-metre precision. This tool outputs the full 10-digit form.
Geohash interleaves the binary representations of latitude and longitude, alternating bits between the two, then encodes the result in base-32 characters. Shorter hashes cover larger cells; each additional character roughly halves the area. Geohashes are widely used in databases (MongoDB, Redis, Elasticsearch) for fast proximity filtering.
Worked example — Greenwich Observatory
The Royal Observatory in Greenwich, London is near latitude 51.4778, longitude –0.0014 (just west of the prime meridian). Running it through the formatter produces:
- DMS: 51° 28’ 40.08” N, 0° 0’ 5.04” W
- DDM: 51° 28.668’ N, 0° 0.084’ W
- UTM: 30U 699956E 5710160N
- MGRS: 30UXC9995610160
- Geohash: gcpuuz (6-char, ~1.2 km cell)
Limits and caveats
UTM and MGRS are defined for latitudes between 80° S and 84° N. The polar regions use the separate Universal Polar Stereographic (UPS) system, which is outside the scope of this tool — inputs near or beyond those limits are flagged. All outputs use the WGS84 datum, which is what smartphones, Google Maps, and most modern GPS receivers use. If your source data is on a different datum (NAD83, ED50, OSGB36), a datum conversion is needed first, as shifts can range from a few centimetres to hundreds of metres.