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How to convert decimal degrees to DMS and back

How to convert decimal degrees to DMS and back

A map app gives 35.6892, a survey sheet or flight plan wants 35° 41′ 21.12″ N. Split the fraction of a degree into minutes and seconds, add a hemisphere letter, and both forms point at the same spot.

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Same point, three ways to write it

Web maps and most apps use decimal degrees, such as 35.6892. Paper maps, surveying, and aviation use degrees, minutes, and seconds: 35° 41′ 21.12″ N. Marine and handheld GPS units often use degrees and decimal minutes: 35° 41.352′ N. All three describe the same point.

Mixing them up moves the point. Typing 35.4121 because a coordinate read 35° 41′ 21″ puts it about 30 km south of where you meant. Dropping the minus sign from a longitude west of Greenwich puts it on the other side of the world.

Convert with one tool, check with another

The Lat/Long to DMS Converter turns decimal degrees into DMS and reads DMS or decimal minutes back into decimal degrees. The sign becomes the hemisphere letter: positive latitude is N and negative is S, positive longitude is E and negative is W. You choose how many decimals the seconds get. Latitude must be between −90 and 90 and longitude between −180 and 180, and coordinates are taken as WGS 84 with no datum conversion.

To confirm a converted point is where you expect, the Distance Calculator accepts either form and gives the straight-line distance and the bearing between two points. If a point that should be next door comes back hundreds of kilometers away, a sign or a field was swapped.

Convert decimal degrees to DMS

  1. Take the decimal coordinate without its sign, for example 35.6892.
  2. The whole number is the degrees: 35.
  3. Multiply the fraction by 60 for minutes: 0.6892 × 60 = 41.352, so 41 minutes.
  4. Multiply what is left of the minutes by 60 for seconds: 0.352 × 60 = 21.12 seconds.
  5. Add the hemisphere from the sign. A positive latitude is N, so the result is 35° 41′ 21.12″ N.
  6. To go back, add degrees + minutes ÷ 60 + seconds ÷ 3,600, and make the result negative for S or W.

Precision and other limits

  • Every decimal place counts. Four decimals in decimal degrees pin a point to about 11 m at the equator, and five decimals to about 1.1 m.
  • No datum conversion is done. Coordinates from an older local datum need converting to WGS 84 first.
  • The distance is a straight line over a sphere. Roads are usually 20% to 40% longer.

Frequently asked questions

How do I write coordinates in decimal degrees?

Write the degrees with the fraction as decimals, latitude first, and use a minus sign for south and west, for example 35.6892, 51.3890.

What is 35.6892 in degrees, minutes, and seconds?

35° 41′ 21.12″ N, when it is a latitude.

What does a negative longitude mean?

A point west of Greenwich. −0.1276 is 0° 7′ 39.36″ W.

How many decimal places do I need?

Five decimal places locate a point to about a meter, which is enough for most uses.

Tools used in this guide

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