GPS Positions and how to convert them

3 different GPS formats

There is 3 different GPS formats, and confusion often arrises when having to enter coordinates in a different format than the information is stated in. The first step in any conversion is to recognize in what format you have your position in.

First of all let’s take a look at the symbols:
° : degree
‘ : minute
“ : second

• Decimal Degrees (DD). h ddd.ddddd°
• Degrees Decimal Minutes (DDM). h ddd° mm.mmm’
• Degrees Minutes Seconds (DMS). h ddd°  mm’  ss.s” 

The example used is a position of the U-boat U251, here seen in DDM from a Honningbird GPS

Decimal Degrees (DD) to Degrees Decimal Minutes (DDM)

56.57435 take the decimal part and multiply with 60 (0.57435 * 60) giving 34.461 — > 56° 34.461

Degrees Decimal Minutes (DDM) to Decimal Degrees (DD)

56° 34.461 take the decimal part and divide with 60 (34.461 / 60) giving 0.57435 -> 56.57435

Degrees Decimal Minutes (DDM) to Degrees Minutes Seconds (DMS)

56° 34.461 is split into 56° 34′ (0.461 * 60 = 27,66), giving 56° 34′ 27.66″

Degrees Minutes Seconds (DMS) to Decimal Degrees (DDM)

56° 34′ 27.66″ is split into 56° 34′ (27.66 / 60 = 0,461), giving 56° 34.461′

Degrees Minutes Seconds (DMS) to Decimal Degrees (DD)

1 minute is equal to 60 seconds.
1 degree is equal to 1 hour, that is equal to 60 minutes or 3600 seconds.

To calculate decimal degrees, we use the DMS to decimal degree formula below:
Decimal Degrees = degrees + (minutes/60) + (seconds/3600)

DD = d + (min/60) + (sec/3600)

56° 34' 27.66" -> 56 + (34/60) + (26.66 / 3600),giving (56,57435)