Days between dates
| Span | Days | Weeks |
|---|---|---|
| One week | 7 | 1 |
| One fortnight | 14 | 2 |
| Four weeks | 28 | 4 |
| One common year | 365 | 52.14 |
| One leap year | 366 | 52.29 |
| Two years | 730 or 731 | 104.3 |
| One decade | 3,652 or 3,653 | 521.7 |
The days between two dates is the plain difference: 1 January to 31 January is 30 days. Counting both end days instead gives 31. Which of the two you want depends entirely on the question, which is why the panel offers both.
How to count days between dates
Inclusive counting is the single most common source of off-by-one disputes. "How many days is my holiday" counts both the first day and the last, so a Monday-to-Friday break is five days. "How many days until Friday" counts the gap, so from Monday it is four. Contracts, notice periods and hire agreements each pick one convention and rarely say which.
When it matters, state the two dates instead of the count. "From 1 to 5 June inclusive" can only be read one way; "five days from 1 June" can be read three. The switch on this panel adds or removes exactly one day, so where a figure elsewhere is out by one, that is almost always what happened.
What people use it for
- Working out a notice period
- Counting days of leave or hire
- Checking a deadline
- Measuring the gap between two events
Questions
Subtract one from the other. 1 January to 31 January is 30 days between, or 31 counting both days.
Yes for a period you occupy: a holiday, a hire, a tenancy. No for a countdown to a date, where the target day has not been used up yet.
Yes. Any span crossing 29 February gains a day, so a year here reads as 365 or 366. The leap rule itself, century exceptions and all, is set out on the date calculator.
No. The gap is the same either way round, and the breakdown always reads from the earlier date to the later one.