Date Calculator

It depends on what you are counting. A contract that runs from the 1st to the 30th is 29 days of gap and 30 days of coverage. Hotel nights, loan interest, and notice periods are exclusive. Holiday entitlement, event days, and anything where you were physically present on both endpoints is inclusive. The checkbox exists because both are correct in their own context.

Because months have different lengths and years have leap days. The breakdown walks the calendar: it subtracts the year, then the month, then borrows the actual length of the previous month if the day-of-month went negative. Dividing total days by 365 is an approximation that drifts by a day every four years.

No. Every day in the range is counted. There is no weekend exclusion and no public holiday calendar, which would need a country and a year to be meaningful. For a working-day count, take the total, divide by 7, multiply by 5, and adjust for the partial week and any holidays by hand.

No. All the arithmetic runs in UTC, where every day is exactly 24 hours. Tools that compute this in local time can be off by one when a range crosses a clock change, because one of the days was 23 or 25 hours long and the division rounds unexpectedly.

Not in this tool. The add and subtract mode shifts by a whole number of days only. Adding months is genuinely ambiguous (what is one month after 31 January?), and rather than pick a convention silently, the tool keeps to days, where the answer is never in doubt.