Add or subtract days, weeks, months or years from any date — in calendar days or business days — and see the resulting date, its weekday and the true span crossed. Runs entirely in your browser — your numbers never leave this device.
Calendar mode counts every day, weekends included. Switch to business days to count only Monday to Friday.
Enter a start date, an amount, and a unit — days, weeks, months or years — then choose add or subtract. Day and week steps move by whole calendar days. Month and year steps move the calendar month and clamp the day when the target month is shorter: 31 January plus one month lands on 28 February (29 in a leap year), because February has no 31st. The result is shown with its weekday, plus the number of calendar days actually spanned, which is the honest check whenever months of different lengths are involved.
Business-days mode changes what a 'day' means: each step lands only on Monday to Friday, stepping over Saturdays and Sundays, so adding 30 business days to a Monday lands six calendar weeks later on another Monday. A week in business mode counts as 5 business days. Months and years are always calendar units — there is no standard 'business month' — and the tool says so when you combine them. Public holidays are not skipped, because they differ by country and employer.
Everything is computed on whole calendar days rather than timestamps. That matters more than it sounds: a timestamp-based tool can land an hour short after a daylight-saving change and report the previous evening's date, while a day-counting tool always lands on the exact calendar date.
Steps land only on Monday to Friday. Adding 1 business day to a Friday gives the following Monday, and adding 30 business days covers 42 calendar days (six full weeks). It applies to day and week units; months and years stay calendar-based, and public holidays are never skipped automatically.
Month-end clamping. February has no 30th or 31st, so a monthly step from the 31st lands on February's last day — the 28th, or the 29th in a leap year. The same rule makes 29 February + 1 year land on 28 February. The alternative (spilling into 3 March) would drift recurring dates further every month.
No — the start date is day zero and the result is 90 days later, matching how deadlines and contract terms are normally counted. 1 November 2026 + 90 days = 30 January 2027. If your term sheet counts the start day itself, add one extra day to the amount.
Yes — choose Subtract and the same units and modes apply in reverse, including business days stepping backwards over weekends. Subtracting is the quickest way to find a start date from a deadline: 364 days before 31 December 2026 is 1 January 2026.
No. The calculator counts whole calendar days, not hours, so the spring and autumn clock changes cannot pull a result onto the wrong date — a flaw timestamp-based calculators genuinely have.
No. It runs entirely in your browser; your dates are never uploaded, stored or tracked.
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