What is the difference between decimal degrees and DMS?
They name the same point two ways: 47.6205° N is 47° 37′ 13.8″ N. Keep the whole degrees, multiply what is left by 60 for minutes, then multiply the minutes’ remainder by 60 for seconds. Most apps and forms take decimal degrees.
Converting by hand
Take 47.6205. The degrees are 47. The rest, 0.6205, times 60 is 37.23, so the minutes are 37. The rest of that, 0.23, times 60 is 13.8 seconds: 47° 37′ 13.8″. To go back, divide the minutes by 60 and the seconds by 3,600 and add both to the degrees.
Minus signs and N, S, E, W
In decimal degrees a minus sign means south for latitude and west for longitude. In degrees, minutes and seconds the letter says it instead, so −122.3493 becomes 122° 20′ 57.5″ W. Swapping latitude and longitude, or losing the minus sign, puts the point on another continent, so check both before you send them.
Degrees and decimal minutes
GPS receivers, aviation and geocaching often use a third form, degrees and decimal minutes: 47° 37.230′ N, 122° 20.958′ W. It is the same point again; the minutes simply keep their decimals instead of being split into seconds.
How many decimals you need
At the equator, one degree of latitude is about 111 km, so five decimal places step about 1.1 m and six about 11 cm. More decimals don’t make a reading more accurate: a phone’s position is only as good as its accuracy radius. GPS.gov puts a smartphone’s usual accuracy at about 4.9 m (16 ft) under open sky, and worse near buildings, bridges and trees.