Who Uses DDM
DDM is the standard format for aviation VFR charts worldwide. Garmin GPS devices default to DDM. The FAA and ICAO use DDM for waypoint notation. Marine chart plotters commonly display in DDM. Search and rescue teams often coordinate in DDM because it matches standard GPS output.
- Pilots (VFR and IFR charts)
- Marine navigators
- Garmin GPS users
- Search and rescue
How to Read DDM Coordinates
- 48°51.504'N: 48 degrees, 51.504 decimal minutes North.
- 2°17.670'E: 2 degrees, 17.670 decimal minutes East.
- To convert to DD: divide the decimal minutes by 60 and add to degrees.
- 51.504 minutes ÷ 60 = 0.8584°, so 48 + 0.8584 = 48.8584°
Converting DDM by Hand
DDM to DD: DD = Degrees + (DecimalMinutes/60). DD to DDM: DecimalMinutes = (DD - floor(DD)) × 60.
Frequently Asked Questions
How do I change my Garmin to DDM?
Go to Setup → Position Format → Select "hddd°mm.mmm'" (which is DDM). This is usually the factory default.
Why do pilots use DDM instead of DMS?
Aviation charts measure distances in nautical miles. 1 minute of latitude = exactly 1 nautical mile, so DDM makes distance calculations intuitive — 0.5 minutes = 0.5 nautical miles.
Is DDM the same as DMS?
No. DMS has whole minutes and decimal seconds (48°51'30.24\"N). DDM has decimal minutes and no seconds (48°51.504'N). Both are derived from the same underlying DD value.