Decimal degrees

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(dd) are often used in Geographic Information Systems (GIS), web-mapping applications such as Google Maps, and GPS devices to express latitude and longitude coordinates, rather than expressing geographic coordinates with degrees, minutes, and seconds (dms).

[edit] Accuracy

A value in decimal degrees to an accuracy of 4 decimal places is accurate to 10meters at the equator. A value in decimal degrees to 5 decimal places is accurate to 1meter at the equator. Because the earth is a sphere and not flat, the accuracy of the longitude part of the coordinates increases the further from the equator you get. The accuracy of the latitude part does not increase.

[edit] Example

With DMS, the geographic coordinates of the United States Capitol are "38° 53' 23" N, 77° 00' 32" W". In decimal degrees, West and South are considered to be negative numbers and the DMS is converted to degrees using the formula (D + M/60 + S/3600). Thus the decimal degree representation of the U.S. capitol is "38.889722°, -77.008889°".