Decimal Degrees to Decimal Minutes
Convert decimal degrees to degrees decimal minutes (DDM) — and back — instantly. The format used by marine GPS and aviation. Free, runs in your browser.
Decimal Degrees → Decimal Minutes
Decimal Minutes → Decimal Degrees
Reading coordinates off a boat's chartplotter or a flight plan? Those are almost always in degrees and decimal minutes — like 40° 45.480' N. Paste your decimal degrees to get that format, or enter the minutes to get plain decimal for an app or API. One minute of latitude is one nautical mile, which is why sailors live in this format. Runs entirely in your browser.
Decimal Degrees vs Decimal Minutes
There are three common ways to write a coordinate. Decimal degrees (40.7580) is what software wants. Full DMS (40° 45′ 28.8″) appears on paper maps. In between is degrees decimal minutes (DDM) — 40° 45.48′ — the format built into marine GPS chartplotters and aviation, because one minute of latitude equals exactly one nautical mile.
Need the seconds-based format instead? Use the DMS ↔ decimal degrees converter.
Frequently Asked Questions
How do I convert decimal degrees to decimal minutes?
Keep the whole number as the degrees. Multiply the fractional part by 60 to get the minutes, kept as a decimal. For example 40.7580° → 40° and 0.7580 × 60 = 45.48′, giving 40° 45.48′ N.
What is degrees decimal minutes (DDM)?
DDM (also written DMM) expresses a coordinate as whole degrees plus decimal minutes, like 40° 45.480′ N. It is the format used by most marine GPS chartplotters, aviation, and apps like Google Maps when you enter minutes — sitting between full DMS (degrees-minutes-seconds) and plain decimal degrees.
How do I convert decimal minutes back to decimal degrees?
Divide the minutes by 60 and add to the degrees: decimal = degrees + minutes/60. So 40° 45.48′ = 40 + 45.48/60 = 40.7580. Apply a negative sign for South or West.
Why do sailors and pilots use decimal minutes?
Nautical charts and GPS units are built around minutes of latitude — one minute of latitude equals one nautical mile. Keeping minutes with a decimal (rather than converting to seconds) makes distance and speed calculations quick and natural.