What's the most natural way of handling end-dates and midnight?

Question

We run promotions that end at midnight. I.e. 24:00. So if I want something to run from the 24th to the 25th it really means 0:00 24th -> 0.00 25th as far as the implementation details go. Should I tell humans:

1. Promotion ends on the 25th

2. Promotion ends at midnight on the 25th

3. Promotion ends at 23:59 on the 25th

4. Promotion ends on the 24th [since it stops after the 24th is over]

Which is prefered? Is there a better way?

Answer 1

Not sure this is the right forum for this, but:

Your current examples refer to different times, but the approach of #3 is common and unambiguous.

In the US, we have no term that explicitly refers to the end of the day, like "24:00". Although one might argue that this is how "midnight" is used and interpreted, or how it should be, using it this way will result in confusion. Perhaps because it has no contrast, like "00:00", some people consider it to be equivalent to "12:00 AM" (i.e., a time, rather than a word we use to designate the end of the day), which is necessarily the beginning of the day. I think it makes more sense to think of midnight as an instant, that does not sit on either day.

Saying "through [date]" could work, but as with "on [date]" some people might question whether or not the cutoff time is the end of the day.