Add or subtract days from a date, or find the difference between two dates.
Wednesday, September 16, 2026
2026-09-16
A 90-day deadline
Add days to a start date
90Working days
Count business days only
30Project length
Difference between two dates
2026-01-15Add an interval, subtract one, or measure the difference between two dates.
Choose days, weeks, months, years or business days. Business days skip Saturdays and Sundays.
Differences show both the calendar breakdown and the raw totals, so you can use whichever the situation calls for.
Adding a month to 31 January gives 28 or 29 February rather than overflowing into March — the behaviour people actually expect.
Contractual and legal deadlines are usually counted in working days, which is tedious and error-prone to do by hand.
“Two months and five days” and “64 days” answer different questions, so both are shown.
Three calculations in one tool: add an interval to a date, subtract one from it, or measure the gap between two dates. Intervals can be days, weeks, months, years or business days, and month arithmetic rolls correctly — 31 January plus one month is the end of February, not 3 March. Differences are reported both as calendar years, months and days and as raw totals, with weekdays and weekend days separated for anything with a working-day deadline.
Keep going
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