Coordinates Converter: DD, DMS, DDM and UTM
Enter a latitude and longitude in Decimal Degrees and this tool converts them instantly into Degrees-Minutes-Seconds (DMS), Degrees-Decimal-Minutes (DDM), and Universal Transverse Mercator (UTM). Every output updates as you type. The step-by-step panel shows exactly how each conversion is done.
The four GPS coordinate formats explained
There are four common ways to write the same geographic point. Decimal Degrees (DD) is the format used by most digital mapping applications and web APIs: latitude and longitude are each expressed as a single number, positive for North and East, negative for South and West (e.g. 40.7128, -74.0060 for New York City). Degrees-Minutes-Seconds (DMS) is the traditional navigator format that splits each degree into 60 arcminutes and each arcminute into 60 arcseconds with a compass letter (e.g. 40deg 42' 46" N, 74deg 0' 21" W). Degrees-Decimal-Minutes (DDM, also called DM) keeps the whole degrees but expresses the remaining fraction as a decimal minute rather than splitting into minutes and seconds. Universal Transverse Mercator (UTM) is a Cartesian metric grid: it gives an easting and a northing in metres within a numbered zone, making distance calculations straightforward without trigonometry.
How to convert between formats
Converting DD to DMS works in two passes. First, take the integer part of the absolute value as the degrees. Multiply the remaining decimal by 60 to get minutes; take its integer part. Multiply the remaining decimal again by 60 to get seconds. For example, 40.7128 deg: degrees = 40, minutes = floor(0.7128 * 60) = 42, seconds = (0.7128 * 60 - 42) * 60 = 46.08. Prefix with N/S (latitude) or E/W (longitude) based on the sign. DDM stops after the minutes step and keeps the decimal there: 40deg 42.768'. Converting to UTM requires the full Transverse Mercator projection with WGS84 ellipsoid parameters (semi-major axis a = 6,378,137 m, flattening 1/298.257). The zone runs every 6 degrees of longitude, a scale factor k0 = 0.9996 is applied, and a false easting of 500,000 m is added so easting values stay positive. Latitudes in the Southern Hemisphere also get a 10,000,000 m false northing.
Which format should you use?
Use Decimal Degrees when working with programming APIs, spreadsheets, CSV files, or modern web maps such as Google Maps, Mapbox, or OpenStreetMap. The simple numeric format is easiest to parse programmatically. Use DMS when reading from or entering into traditional nautical charts, aviation charts, or older GPS handhelds; it is also the legally required format in many paper navigation documents. Use DDM for Garmin and Magellan consumer GPS units, which often store coordinates in that format by default. Use UTM when doing field measurements, GIS analysis, or surveying where you need to calculate straight-line distances easily: 1,000 metres of easting or northing is exactly 1 km with no spherical correction needed within a single zone.
UTM zones and edge cases
The world is divided into 60 UTM zones, each 6 degrees of longitude wide, numbered 1 (starting at 180 deg W) to 60 (ending at 180 deg E). Each zone is further divided into 8-degree latitude bands lettered C through X (excluding I and O to avoid confusion with 1 and 0). Norway and Svalbard are handled by special zone rules to prevent odd-shaped zones: zone 32 is extended to cover Norway between 3 and 12 degrees E, and four zones (31, 33, 35, 37) are widened in the Arctic band (72 to 84 degrees N) to keep Svalbard in two instead of four zones. UTM is not defined above 84 degrees N or below 80 degrees S; polar regions use the UPS (Universal Polar Stereographic) system instead.
Coordinate format precision guide
| Format | Example | Smallest unit | Approx. ground distance |
|---|---|---|---|
| DD (1 dp) | 40.7 deg N | 0.1 deg | about 11 km |
| DD (2 dp) | 40.71 deg N | 0.01 deg | about 1.1 km |
| DD (4 dp) | 40.7128 deg N | 0.0001 deg | about 11 m |
| DD (5 dp) | 40.71280 deg N | 0.00001 deg | about 1.1 m |
| DD (6 dp) | 40.712800 deg N | 0.000001 deg | about 11 cm |
| DMS (whole sec) | 40deg 42' 47" N | 1 arcsecond | about 31 m |
| DMS (0.01 sec) | 40deg 42' 46.08" N | 0.01 arcsecond | about 31 cm |
| DDM (0.001 min) | 40deg 42.767' N | 0.001 arcminute | about 1.9 m |
| UTM easting/northing | 583960 m E | 1 metre | 1 m |
Approximate ground distance per unit at the equator (WGS84). Accuracy degrades toward the poles for DD and DMS formats.
Frequently asked questions
What is the difference between DD and DMS?
Decimal Degrees (DD) expresses latitude and longitude as a single decimal number (e.g. 40.7128). Degrees-Minutes-Seconds (DMS) splits that same angle into degrees, arcminutes (1/60 of a degree) and arcseconds (1/3600 of a degree), written with a compass direction such as 40deg 42' 46.08" N. Both represent exactly the same point; the format is just a matter of convention. Digital tools generally prefer DD, while traditional navigation documents and older GPS devices use DMS.
How many decimal places do I need for accurate GPS coordinates?
Five decimal places gives you about 1.1 metre precision at the equator, which is sufficient for most everyday navigation. Six decimal places gives about 11 centimetres, which matters for surveying and precision mapping. Four decimal places is enough for identifying a city block. Fewer than four places are only useful for rough regional location. The precision of your GPS receiver or data source is usually the limiting factor, not the number format.
What is a UTM zone?
A UTM zone is a 6-degree-wide north-south strip of longitude. There are 60 zones in total, numbered 1 to 60 starting from 180 degrees West and running east. Within each zone, coordinates are expressed in metres east (easting) and metres north (northing) of a false origin, so all values are positive. Easting starts at a false 500,000 m on the central meridian; northing starts at 0 for the equator in the Northern Hemisphere, or 10,000,000 m for the Southern Hemisphere (false northing). New York City is in Zone 18T; London is in Zone 30U.
Can I convert UTM back to latitude and longitude?
Yes. The inverse UTM calculation uses the same WGS84 ellipsoid parameters in reverse. You need the zone number, hemisphere (N or S), easting and northing. Most GIS platforms and surveying software include this function. This calculator focuses on DD to other formats; dedicated UTM-to-DD converters are widely available for the reverse direction.
Why does my GPS show DDM instead of DD?
Many consumer GPS units, especially older Garmin and Magellan handhelds, default to Degrees-Decimal-Minutes (DDM) because it was common in nautical charts and aviation. The format looks like 40deg 42.767' N. You can usually change the display format in the settings menu. This calculator shows DDM alongside DD and DMS so you can cross-check.
Are latitude and longitude the same everywhere in the world?
Latitude and longitude values depend on the datum (reference ellipsoid) used. This calculator uses WGS84, the global standard behind GPS and Google Maps. Older national surveys used different datums such as NAD27 (North America) or OSGB36 (Great Britain), which can differ from WGS84 by up to 100 metres or more. Always confirm the datum when importing coordinates into a professional GIS.
What does the band letter in UTM mean?
The band letter identifies an 8-degree latitude strip. The letters run C to X from south to north (skipping I and O). For example, Zone 18T covers eastern North America between latitude 48 and 56 degrees North. The zone number combined with the band letter uniquely locates any point on Earth within about 800 km x 800 km. MGRS (Military Grid Reference System) uses these same zone/band designators and adds a 100 km grid square identifier.