Decimal Degrees to DMS Converter

In short To go from decimal degrees to degrees, minutes and seconds: the whole number is the degrees, the fractional part times 60 gives the minutes, and the remainder of that times 60 gives the seconds. The sign becomes a hemisphere letter and is then dropped, so −0.1278 becomes 0° 7′ 40.1″ W. There is a third notation that matters more than most people expect: degrees and decimal minutes, written 51° 30.443′ N. It survives because one minute of latitude is one nautical mile by definition, so a marine or aviation chart in DDM lets a navigator read distance straight off the latitude scale — which is exactly why GPS receivers, chartplotters and aviation systems still default to it. All three notations describe the same number, and the conversions between them are exact. The one thing to watch is rounding at the boundary: 59.999 seconds must carry up to the next whole minute rather than being printed as 60″, and the same applies to minutes rolling into degrees. A surprising number of converters print 51° 30′ 60.00″, which is not a valid coordinate.