Date Difference Calculator

Calculate the exact number of days, months, and years between two dates. Also shows weeks, hours, and minutes.

This calculator reports the gap between two dates two different ways at once. Total Days, Total Weeks, Total Hours, and Total Minutes are all built from one raw millisecond difference between the two dates, always taking the absolute value so the order you enter them in doesn't flip the sign (line 18) -- Total Hours and Total Minutes are just that day count multiplied out (lines 24-25), so they inherit whatever rounding already happened at the day level rather than being computed independently to the minute. Total Months and Total Years take a different, approximate approach: they divide Total Days by 30.4375 and 365.25 respectively (lines 22-23) -- the average lengths used to smooth over the fact that real months and years vary -- so they won't always match calendar counting exactly. The Duration summary next to them, by contrast, is built the more precise way: an exact year/month/day breakdown computed the same way you'd subtract by hand, borrowing a real calendar month's length whenever the day component goes negative and a year whenever the month component does (lines 28-40), then flipped positive if the end date actually came before the start date (lines 42-46). Start Year moves Total Days more than any other single input in the direction you'd expect -- pushing the start date later shrinks the gap -- while End Year moves it the same amount in the opposite direction, growing the gap as the end date moves later. The calculator does not account for time zones; both dates are treated as local calendar dates with no time-of-day component.