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 you want depends entirely on the question, which is why this tool 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 and last day, 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, the safe move is to state the two dates rather than the count.
Questions
Subtract one from the other. 1 January to 31 January is 30 days between, or 31 counting both days.
For a duration you occupy — a holiday, a hire. Yes. For a countdown to a date, no.
Yes. Any span crossing 29 February gains a day.
No. The gap is the same; the direction row just tells you which way round they are.
365, or 366 in a leap year — which is every year divisible by four, except centuries not divisible by 400.