Coordinates: ddd.dddd, ddd mm.mm or ddd mm ss?

In My Humble Opinion
1

What’s the best format to give latitude and longitude coordinates in, given all the plusses and minuses of the three common ways?

ddd.dddd or decimal degrees:
Easiest to calculate with in general. The only format that sometimes tells you it’s the one in use (because two of the digits might be >5 which would rule out the other formats). Also, the lowest rounding error given the same number of significant digits.

ddd mm.mm or degrees and decimal minutes:
The standard in geocaching (apparently). Also the standard in NMEA communications protocol. One minute of arc is the same as one nautical mile on the Earth’s surface, so for certain problems this is the easiest to calculate with.

dd mm ss.s or degrees, minutes, decimal seconds:
Hard to say what’s superior about this one, but IIRC USGS maps use this format.

2

I use both degrees minutes seconds and decimal degreees, usually based on what format my input data are in and what the software can use. Decimal degrees is easier to calculate with.

What’s the difference between decimal degrees and degrees decimal minutes?

3

I, of course, realized the answer to my question right away. I’ve never used degrees decimal minutes and I’ve never had software that wanted that hybrid, but apparently the geocachers like it.

4

It seems to me that ddd mm.mm is the most common format these days - ddd mm ss seems to be dying out.

But ddd.dddd really seems simpler and more sensible - sort of like decimal currency vs. pounds-shillings-pence.

And do you agree that west longitudes should be negative? It makes sense to me.

5

Negative west longitudes, yeah.

6

The feds require me to report my data in ddd mm ss.ss so that’s how it is stored in our database. But my users often want to convert what I give them to ddd.dddd. Some want negative west longitude. If I got to choose, I’d go for decimal degrees.