Coordinate Converter - DD to DMS & UTM

Formula

DD = Deg + Min/60 + Sec/3600

To convert DMS to Decimal Degrees: Add degrees, minutes divided by 60, and seconds divided by 3600. Apply negative sign for South or West directions.

Worked Examples

Example 1: DMS to DD: Lower Manhattan

Problem:A survey note gives 40° 42' 46" N, 74° 0' 21" W. Convert both to decimal degrees for a GeoJSON file.

Solution:Latitude: 40 + 46/3600 + 42/60 = 40 + 0.700000 + 0.012778 = 40.712778. Longitude: 74 + 0/60 + 21/3600 = 74.005833, then negate because the direction is West.

Result:40.712778, -74.005833

Example 2: DD to DMS: Sydney Opera House

Problem:Google Maps reports -33.8688, 151.2093. Convert to degrees, minutes and seconds for an aviation chart.

Solution:Latitude: whole degrees 33; 0.8688 x 60 = 52.128, so 52 minutes; 0.128 x 60 = 7.68 seconds; sign is negative so direction is S. Longitude: whole degrees 151; 0.2093 x 60 = 12.558, so 12 minutes; 0.558 x 60 = 33.48 seconds; sign is positive so direction is E.

Result:33° 52' 7.68" S, 151° 12' 33.48" E

Frequently Asked Questions

What is DD vs DMS?

DD (Decimal Degrees) expresses coordinates as single decimal numbers (e.g., 40.7128). DMS (Degrees Minutes Seconds) breaks them down into base-60 units (e.g., 40° 42' 46" N).

How accurate are GPS coordinates?

5 decimal places (e.g., 40.12345) gives accuracy to about 1.1 meters. 6 decimal places is accurate to ~11cm. 4 decimal places is accurate to ~11 meters (street level).

How to find coordinates on Google Maps?

On desktop, right-click any point and select the numbers at the top of the menu. On mobile, long-press a location to drop a pin and see coordinates in the search bar.

Can coordinates locate a specific house?

Yes. With 5-6 decimal places of precision, coordinates can pinpoint a specific front door or even a chair in a room.

Background & Theory

**Coordinate Systems:** **Latitude (Lat):** - Horizontal lines - 0° at Equator - +90° at North Pole, -90° at South Pole - ~69 miles (111 km) per degree **Longitude (Lng):** - Vertical lines converging at poles - 0° at Prime Meridian (Greenwich) - +180° East, -180° West - Distance per degree varies: ~69 miles at equator, 0 at poles **Conversion Formula:** $$DD = Degrees + \\frac{Minutes}{60} + \\frac{Seconds}{3600}$$ **Example:** 40° 30' 30" $$DD = 40 + \\frac{30}{60} + \\frac{30}{3600} = 40 + 0.5 + 0.00833 = 40.50833$$ **Datums:** Coordinates depend on the "Datum" (model of Earth's shape). WGS84 is the standard for GPS and Google Maps. Coordinates from older maps (NAD27) may be off by hundreds of meters if not converted.

History

The system of latitude and longitude was developed by ancient Greek astronomers and geographers. Eratosthenes (3rd century BC) invented the system of coordinate lines. Hipparchus (2nd century BC) was the first to use latitude and longitude to specify locations. Ptolemy (2nd century AD) further refined the grid system in his "Geography," assigning coordinates to thousands of places. The measurement of longitude was a major scientific challenge for centuries (the "Longitude Problem"), as it required precise timekeeping at sea. It was solved in the 18th century by John Harrison's invention of the marine chronometer. The Prime Meridian at Greenwich was established as the international standard 0° longitude in 1884. GPS (Global Positioning System) revolutionized coordinates in the late 20th century, allowing anyone to find their precise location instantly using satellite signals.