This date and time calculator finds the duration between two dates or times, adds or subtracts intervals, and counts working days — handling the awkward arithmetic of months, leap years, and time zones that trips up manual counting.
Durations and date maths
Working out how long is between two dates, or what date falls a given number of days ahead, is deceptively fiddly: months have different lengths, leap years add a day, and counting on fingers invites off-by-one errors. The calculator does it precisely — the gap between two dates in days, weeks, months, or years, or a new date after adding or subtracting an interval — so deadlines, ages, and anniversaries come out right.
A common subtlety is whether both endpoints count. Counting the days you are away on holiday, for instance, includes both the first and last day, whereas a pure difference does not. The calculator makes the basis clear so the answer matches the question you are actually asking.
Working days and time zones
For business planning, the count that matters is often working days, excluding weekends (and optionally holidays), which is how lead times and notice periods are usually expressed. The calculator can count those rather than calendar days. It also helps with time-zone differences, so you can line up a call or a deadline across regions without mental arithmetic and the risk of being an hour — or a day — out.
Counting the days from 1 March to 1 June in a non-leap year.
- March has 31 days, April 30, May 31.
- Total = 31 + 30 + 31 = 92 days.
- So 1 June is 92 days after 1 March.
There are 92 days between 1 March and 1 June in a common (non-leap) year.
