How it works
Choose a start date, decide whether to add or subtract, and enter an amount and a unit. Days and weeks are counted exactly, so leap years and different month lengths are handled for you. For months and years the calculator keeps the same day of the month, and if that day does not exist in the target month it uses the last day instead. Adding one month to January 31, for example, gives February 28 (or 29 in a leap year).
Common questions people use it for
- What is the date 90 days from today? Leave the start date as today and enter 90 days.
- Deadlines and notice periods: 30 days from a signing date, or 6 weeks before an event.
- Warranties and returns: the last day of a 12-month warranty or a 30-day return window.
- Planning: a due date, a course start, a project milestone or a trip countdown.
Calendar days versus business days
This calculator counts every calendar day, including weekends and public holidays. If a contract or shipping estimate uses business days, the resulting date will usually be later than the one shown here, since weekends and holidays do not count. Check how the deadline is defined before relying on a date.
Does adding 12 months equal adding one year?
Yes. A year is 12 calendar months, so both give the same date. Adding 365 days is different: it lands a day earlier than one year after the start date whenever the period includes February 29.