Coordinate Format Converter – DD, DMS, DDM, UTM, MGRS, Geohash & Plus Code
Geographic coordinates can be expressed in many different notations depending on the application, device, or industry. A GPS receiver might output Decimal Degrees, a surveying instrument might record Degrees Minutes Seconds, a military map uses MGRS, and a database engineer may index locations as Geohashes. This free Coordinate Format Converter handles all seven major formats simultaneously so you never have to perform manual conversions again.
The Seven Supported Coordinate Formats
Decimal Degrees (DD)
The simplest and most machine-readable format. Each axis is a single floating-point number: positive values are North/East, negative values are South/West. Example: 48.8566, 2.3522 for the Eiffel Tower in Paris. DD is the default format for web APIs, Google Maps URLs, GeoJSON, and most modern GIS software.
Degrees Minutes Seconds (DMS)
The traditional sexagesimal notation used in cartography, astronomy, and surveying for centuries. Each axis is split into integer degrees (°), integer minutes (′), and decimal seconds (″) with a hemisphere indicator (N/S or E/W). Example: 48° 51′ 23.76″ N, 2° 21′ 7.92″ E. DMS is still widely used on paper maps, nautical charts, and in legal property descriptions.
Degrees Decimal Minutes (DDM)
A hybrid format where degrees are integers but minutes carry the decimal fraction. Example: 48° 51.396′ N, 2° 21.132′ E. DDM is the default on most marine chart plotters and aviation GPS units because it balances human readability with the precision needed for navigation.
UTM – Universal Transverse Mercator
UTM divides the world into 60 numbered zones (each 6° of longitude wide) and expresses positions as Easting and Northing in metres within each zone. Example: 31N 452602E 5411943N. Because all values are in metres, UTM makes distance and area calculations trivially simple and is the backbone of most national mapping agencies' coordinate systems.
UTM is undefined at the poles (beyond 84°N and 80°S), where the Universal Polar Stereographic (UPS) system takes over. Coordinates in that range will show a polar warning in the converter.
MGRS – Military Grid Reference System
MGRS builds on UTM by adding a two-letter 100 km grid square identifier before the numeric easting and northing. The result is a compact, self-contained reference like 31UDQ52602 11943. NATO militaries, search-and-rescue teams, outdoor navigation apps like Gaia GPS, and geocachers all use MGRS. The converter lets you choose precision from a 4-figure reference (1 km accuracy) to a 10-figure reference (1 m accuracy).
Geohash
A Geohash encodes a coordinate as a short base-32 string: u09tunq. Longer strings represent smaller geographic cells. The format has a useful property: nearby places usually share common prefixes, making it ideal for proximity searches in databases like Elasticsearch, Redis, and MongoDB. Precision 5 gives roughly a 5 km × 5 km cell, while precision 9 gives a 5 m × 5 m cell. The converter lets you adjust precision from 1 to 12 characters.
Plus Code (Open Location Code)
Developed by Google and released as an open standard, Plus Codes encode a location as a 10-character alphanumeric string like 8FW4V75V+8Q. A full 10-character code represents roughly a 14 m × 14 m area. Plus Codes work without internet connectivity and are used extensively in humanitarian aid delivery, emergency services, and postal services in countries that lack formal street addressing.
How the Conversions Work
All conversions use Decimal Degrees as the common intermediate form. DD → DMS uses the floor-divide method: subtract the integer degree, multiply the remainder by 60 to get minutes, multiply the new remainder by 60 to get seconds. UTM conversion applies the Transverse Mercator projection formulae from EPSG:32600 with the WGS84 ellipsoid (semi-major axis 6 378 137 m, flattening 1/298.257223563) as the reference surface. MGRS extends UTM by mapping the easting and northing into 100 km grid squares using the NATO STANAG 2211 letter scheme. Geohash applies the standard base-32 interleaved bit-encoding algorithm. Plus Code uses the Open Location Code specification to produce a hierarchical grid reference.
Typical Use Cases
GIS and mapping: Converting coordinates from a field GPS (often in DMS) into DD for import into QGIS, ArcGIS, or Google Earth. Military and SAR: Sharing an MGRS reference with a team using a map grid. Drone flight planning: Entering UTM zone and waypoints into flight controller software. Database engineering: Generating Geohashes for spatial indexing in NoSQL stores. Addressing: Generating Plus Codes for locations in regions without street addresses.
Accuracy and Limitations
All arithmetic uses JavaScript's 64-bit floating-point representation, which provides approximately 15 significant digits — more than sufficient for any practical navigation purpose. The UTM and MGRS results are accurate to within 1 metre for coordinates between 84°N and 80°S. The Geohash algorithm is exact for the chosen precision level. Plus Code results match the Open Location Code specification to within the grid cell size of the chosen code length. For professional surveying applications requiring sub-centimetre accuracy, dedicated geodesy software with full geodetic corrections should be used.