Latitude and Longitude Converter

Coordinate converter

Decimal degrees, degrees and minutes, DMS

Decimal degrees 36.97833° N, 75.70333° W Signed: 36.97833, -75.70333
FormatLatitudeLongitude
DD36.97833° N75.70333° W
DMM36° 58.700′ N75° 42.200′ W
DMS36° 58′ 42.0″ N75° 42′ 12.0″ W

Type 36 58.7 N, 36°58′42″N, 36.97833 or -75.70333: degrees, minutes and seconds with N, S, E or W, or a minus sign for south and west. A pair pasted into either box, such as 36.97833, -75.70333 copied from a map, fills both. The converter rewrites the numbers only; it doesn’t look up places or change the datum.

A position can be written in decimal degrees (DD), in degrees and decimal minutes (DMM) or in degrees, minutes and seconds (DMS). A degree has 60 minutes and a minute has 60 seconds, so 36° 58.7′ N is 36 + 58.7 ÷ 60 ≈ 36.97833° N in decimal degrees and 36° 58′ 42.0″ N in degrees, minutes and seconds. Type a latitude, a longitude or both in any of these forms above, and the converter shows all three, ready to copy into a chart plotter, a GPS or a spreadsheet.

Latitude and Longitude Formats

The same position near Chesapeake Light, from an example in The American Practical Navigator (Bowditch), in each format:

Format Example How it works
Decimal degrees (DD) 36.97833° N, 75.70333° W Degrees with decimals. Web services such as the U.S. Geological Survey’s write it signed, with a minus sign for south and west: 36.97833, -75.70333.
Degrees and decimal minutes (DMM, also written DDM) 36° 58.700′ N, 75° 42.200′ W Whole degrees, then minutes with decimals. Ships’ electronic chart systems (ECDIS) show positions this way.
Degrees, minutes and seconds (DMS) 36° 58′ 42.0″ N, 75° 42′ 12.0″ W Whole degrees and minutes, then seconds, each from 0 to 59.

Latitude runs from 0° at the equator to 90° at the poles, north or south, and longitude from 0° at the prime meridian through Greenwich, England, to 180°, east or west (NOAA). A latitude never goes past 90° and a longitude never past 180°.

How to Convert Coordinates by Hand

DMM or DMS to decimal degrees: degrees + minutes ÷ 60 + seconds ÷ 3,600 · Decimal degrees to DMM: keep the whole degrees and multiply the decimals by 60 for the minutes · To DMS: keep the whole minutes and multiply their decimals by 60 for the seconds

  • DMM to DD: 36° 58.7′ N is 36 + 58.7 ÷ 60 ≈ 36 + 0.97833 = 36.97833° N.
  • DMS to DD: 75° 42′ 12.0″ W is 75 + 42 ÷ 60 + 12 ÷ 3,600 ≈ 75 + 0.7 + 0.00333 = 75.70333° W.
  • DD to DMM: 36.97833° N keeps 36 degrees, and 0.97833 × 60 ≈ 58.700 minutes: 36° 58.700′ N.
  • DD to DMS: 75.70333° W keeps 75 degrees; 0.70333 × 60 ≈ 42.200 minutes; keep 42 and 0.2 × 60 = 12 seconds: 75° 42′ 12.0″ W.

South latitudes and west longitudes take the letter S or W, or a minus sign in decimal degrees, as in the U.S. Geological Survey’s web services. A second example from Bowditch, a ship leaving Cape Town at 33° 53.3′ S, 18° 23.1′ E, is 33.88833° S, 18.38500° E, or -33.88833, 18.38500 signed, and 33° 53′ 18.0″ S, 18° 23′ 06.0″ E.

Chart Plotter and GPS Position Formats

ECDIS, the electronic chart system of ships, shows latitude and longitude in degrees, minutes and decimal minutes, normally on the WGS 84 datum (Bowditch). Chart plotters let you choose: on a Garmin ECHOMAP, for example, the setting is Settings > Units > Position Format, and Garmin advises not to change it, or the Map Datum next to it, unless you are using a map or chart that specifies a different one (Garmin owner’s manual). Google Maps works in decimal degrees: on a computer, right-click a spot and its latitude and longitude appear at the top of the pop-up, and its search box also takes DMS and DMM (Google Maps Help). Its help page gives one place as 41.40338, 2.17403, as 41°24′12.2″N 2°10′26.5″E and as 41 24.2028, 2 10.4418: paste any of these pairs into either box above and the converter fills both boxes and shows the other formats. Before you type in a waypoint from a chart, a cruising guide or a friend’s message, convert it to the format your plotter shows, so that 36° 58.7′ isn’t entered as 36.58°.

A Format Is Not a Datum

This converter changes how a position is written, not where it is. Positions are measured on a datum, a model of the Earth. GPS receivers default to WGS 84, and NOAA charts of the United States are compiled on NAD 83, which Bowditch calls navigationally equivalent to WGS 84. Older charts and some foreign charts use other datums, and the same latitude and longitude can then fall in a different place: when U.S. charts moved from NAD 27 to NAD 83, positions in Miami changed by 40 meters in latitude and 22 meters in longitude (Bowditch). The datum is printed in the chart’s title block; use the datum the chart names.

How Precise Is Each Format?

One minute of latitude is one nautical mile, 1,852 meters (NOAA), so each place you add to a position narrows it down. Along a line of longitude, one step in the last digit is about:

Last digit Distance In feet or miles
1° 111.1 km 69.0 miles
0.1° 11.1 km 6.9 miles
0.01° 1,111 m 3,646 ft
0.001° 111 m 365 ft
0.0001° 11.1 m 36.5 ft
0.00001° 1.11 m 3.65 ft
1′ 1,852 m 6,076 ft
0.1′ 185 m 608 ft
0.01′ 18.5 m 60.8 ft
0.001′ 1.85 m 6.08 ft
1″ 30.9 m 101 ft
0.1″ 3.09 m 10.1 ft

The figures use 60 nautical miles to a degree; on the real Earth a degree of latitude is between 59.7 and 60.3 nautical miles long (Bowditch). East and west, a step in longitude shrinks with the cosine of the latitude: at 37° north it is about 0.8 times the figure above, and at 60° half of it. The converter prints decimal degrees to 0.00001° (about 1 meter), minutes to 0.001′ (about 2 meters) and seconds to 0.1″ (about 3 meters). To convert a distance in nautical miles to meters, use the Nautical Miles to Meters Converter.

Common Mistakes

  • Decimals read as minutes: 36.58° is not 36° 58′. It is 36° 34.800′ N.
  • The wrong sign: a west longitude without the minus sign or the W lands on the other side of the world.
  • Minutes or seconds of 60 or more: 59.999′ is the most; one more minute is the next degree.
  • A letter and a minus sign together: −75° W is unclear; use one or the other.

On a paper chart, latitude is read on the scale at the sides and longitude on the top and bottom; our guide How to Read a Nautical Chart explains both. To measure a route over water between two places, use the Sea Distance Calculator.

Frequently Asked Questions

How do you convert degrees, minutes and seconds to decimal degrees?

Add the degrees, the minutes divided by 60 and the seconds divided by 3,600. For example, 75° 42′ 12.0″ W is about 75 + 0.7 + 0.00333 = 75.70333° W, or -75.70333 with a minus sign for west.

How do you convert decimal degrees to degrees and minutes?

Keep the whole degrees and multiply the decimal part by 60 to get the minutes. 36.97833° N becomes 36 degrees and about 0.97833 × 60 = 58.700 minutes, or 36° 58.700′ N.

What position format do chart plotters use?

Ships’ electronic chart systems (ECDIS) show degrees, minutes and decimal minutes, such as 36° 58.700′ N. Chart plotters let you choose the format in their settings, so check which one yours shows before you enter a waypoint.

Is west longitude negative?

In decimal degrees, yes: west longitudes and south latitudes take a minus sign and east and north are positive. With N, S, E or W written out, no minus sign is needed.

What is the difference between DMM and DDM?

Nothing. Both mean degrees and decimal minutes, such as 36° 58.700′ N.

How accurate is a position to 0.001 minute?

One minute of latitude is one nautical mile, 1,852 meters, so 0.001 minute of latitude is about 1.9 meters. A step of 0.001 minute of longitude is shorter away from the equator, by the cosine of the latitude.

Sources