How this calculator works
The three formats describe the same angle in different ways. Decimal degrees keep the whole angle in one number. Degrees, minutes and seconds split the fractional part into sixtieths and then into sixtieths of a sixtieth. Degrees and decimal minutes split it once. This page keeps latitude and longitude as positive sizes and applies the hemisphere letter separately, so a west longitude is negative when the signed decimal form is shown.
Formula
decimal = degrees + minutes / 60 + seconds / 3600. Degrees and decimal minutes = degrees + minutes / 60. Latitude runs from 0 to 90 and longitude from 0 to 180 in each direction; S and W make the signed value negative.
Worked example
51°30'26.64"N is 51 + 30/60 + 26.64/3600 = 51.5074 degrees. 0°7'40.08"W is 0 + 7/60 + 40.08/3600 = 0.1278 degrees west, written -0.1278 in signed decimal form.
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Frequently asked questions
Why are minutes and seconds limited to 60?
One degree contains 60 minutes and one minute contains 60 seconds. A value of 60 or more belongs in the next larger unit, so this page rejects it instead of silently carrying it.
How many decimal places should coordinates use?
Five decimal places are about one metre at the equator; six are about ten centimetres. More places suggest more accuracy than most consumer devices provide.
Why does the west longitude become negative?
Signed decimal degrees use positive values for north and east and negative values for south and west. The hemisphere letters remain available in the other two formats.