I made a poll on the fediverse yesterday.

In an international context (e.g., company that works around the globe, or a free software project with participants from several continents), what's the right date format?

The options and results:

  • 80% — 2019-12-13
  • 11% — 19 December 2019
  • 9% — 13/12/2019
  • 0% — 12/13/2019

The one with the name of the month is a different date than the others. That was a typo; mea culpa. Nobody commented on that, though, and I doubt it affected the results.

Here's my commentary. It was a bit of a trick question. Sorry. The first two options are both unambiguous as to which part is day, month, and year. The last two are entirely ambiguous, and require contextual information to interpret correctly. Thus, even though the third option is closest to what I'm used to from my own culture, I think it's utterly unsuitable in an international context.

My own preference is to express the month as a word, or abbreviation, but in many cases being all numeric is easier.

The most important bit is to be clear and unambiguous. Sometimes that means getting used to an unfamiliar notation.