Coordinates Converter

Article — Coordinates Converter

Coordinates Converter Calculator

Geographic coordinates describe any point on Earth using latitude (north-south) and longitude (east-west). Three notation formats are in active use today: decimal degrees (DD), degrees-minutes-seconds (DMS), and degrees-decimal-minutes (DDM). All three describe identical points; the difference is how the numbers are written down.

The calculator converts between all three formats instantly. Type a value in one format and the other two appear in the result panel. Quick-pick buttons load coordinates for New York, London, Tokyo, Sydney, and the equator at Greenwich.

What are geographic coordinates?

Coordinates pin a location on Earth's surface using two numbers. Latitude measures angular distance north or south of the equator from 0° at the equator to ±90° at the poles. Longitude measures angular distance east or west of the prime meridian (Greenwich, England) from 0° to ±180°. Together, a latitude and longitude pair specifies one point.

The coordinate system dates to ancient astronomy and was formalized for navigation in the 17th and 18th centuries when accurate marine chronometers made longitude measurement practical. Modern GPS, satellite imagery, and online maps all rely on the same lat/long framework, just with different notations for the angle values.

Three coordinate formats: DD, DMS, DDM

Decimal degrees (DD) writes each coordinate as a single decimal number with a sign. Positive latitudes are north, negative south; positive longitudes are east, negative west. So Times Square, New York is 40.7484, -73.9857 in DD. This is the format used by Google Maps, geospatial APIs, and scientific data files.

DMS splits each coordinate into degrees, minutes (1/60 of a degree), and seconds (1/60 of a minute), with a hemisphere letter (N/S for latitude, E/W for longitude). The same Times Square point is 40° 44' 54" N, 73° 59' 9" W. This format dominates marine charts, aviation maps, and government property records.

DDM keeps the degrees but uses decimal minutes (no seconds). Times Square is 40° 44.9' N, 73° 59.15' W. DDM is the default output of marine and aviation GPS receivers, and the format encoded in NMEA 0183 sentences from any consumer GPS chip.

DMS to DD coordinates formula

To convert DMS to DD, add the degrees, the minutes divided by 60, and the seconds divided by 3,600. Apply a negative sign for South latitudes or West longitudes. So 40° 44' 54" N = 40 + 44/60 + 54/3600 = 40.74833°.

To convert DD back to DMS, the degrees are the integer part of the absolute decimal. Multiply the fractional part by 60 to get minutes (take the integer). Multiply the leftover fractional minutes by 60 to get seconds. The hemisphere letter comes from the sign of the original DD value.

Coordinate precision and decimal places

Each digit of decimal degrees adds an order of magnitude of precision. At the equator, 1 degree of latitude or longitude equals about 111 km on the ground. So 1 minute of arc equals 1.85 km, and 1 second equals 31 meters. In decimal degrees, that means 0.01° equals 1.11 km, 0.001° equals 111 m, and 0.0001° equals 11.1 m.

Six decimal places of DD give roughly 11 cm precision, which exceeds civilian GPS accuracy (typically 3-5 meters in good conditions). Four decimal places give ~11 m precision, fine for most maps. Two decimal places give ~1.1 km precision, useful for marking a city center but not for finding a specific building.

• 0 decimals = 111 km precision (country-scale)
• 1 decimal = 11.1 km (city-scale)
• 2 decimals = 1.11 km (neighborhood)
• 3 decimals = 111 m (city block)
• 4 decimals = 11.1 m (building)
• 5 decimals = 1.11 m (door)
• 6 decimals = 11.1 cm (sub-foot)

Using coordinates in Google Maps and GPS

Google Maps, Apple Maps, and OpenStreetMap accept all three coordinate formats in their search bars. Paste 40.7484, -73.9857 or 40° 44' 54" N, 73° 59' 9" W and the map zooms to the same point. DD is the most reliable since it has no special characters that can fail to copy correctly.

GPS devices and aviation/marine equipment historically default to DDM because it matches the precision of pre-digital instruments while keeping the math simple for embedded chips. Modern smartphone apps usually display DD but accept DMS input. When sharing coordinates by text or radio, DD has the smallest character count and lowest error rate.

Famous coordinates around the world

Some coordinates are worth memorizing for a sanity check on conversions:

• Equator + Prime Meridian = 0°, 0° (Atlantic Ocean off Africa)
• North Pole = 90° N, longitude undefined
• South Pole = -90°, longitude undefined
• Times Square, NYC = 40.7484° N, 73.9857° W
• Greenwich Observatory = 51.4778° N, 0.0014° W
• Mount Everest = 27.9881° N, 86.9250° E
• Sydney Opera House = 33.8568° S, 151.2153° E
• Tokyo Tower = 35.6586° N, 139.7454° E

Common coordinates mistakes

The first mistake is mixing up latitude and longitude. Latitude always comes first in geographic coordinates (lat, lon), but maths textbooks often use (x, y) where x is the horizontal axis (longitude). Bing Maps, for instance, has historically used (lat, lon) in URLs while some GIS tools default to (lon, lat). Verify the order when copying coordinates between systems.

The second mistake is forgetting the negative sign for West and South. Pasting 73.9857 instead of -73.9857 sends you to the wrong hemisphere. DMS notation avoids this by using N/S/E/W letters, but DD relies on the sign.

The third mistake is treating DDM minutes as integers. The "44.9" in 40° 44.9' is not 44 minutes 9 seconds; it is 44 minutes plus 0.9 of another minute, which equals 54 seconds. Some users mistakenly read 44.9 as "44 and 9 tenths of a second", which gives a completely different location.