Add or Subtract Days from a Date
Find the date a given number of days, weeks, months or years from any starting point — and which day of the week it falls on.
Resulting date
Thursday, 24 September 2026
Day of the week
Thursday
Adding 30 days to Tuesday, 25 August 2026 gives Thursday, 24 September 2026.
Leap years are handled correctly. Month arithmetic clamps to the end of the month, so adding one month to 31 January gives 28 February (or 29 in a leap year) rather than rolling into March.
Other versions of this tool
Frequently Asked Questions
What is this useful for?
Working out deadlines, warranty expiry, notice period end dates, medication schedules, and when a 90-day or 180-day window closes.
How are months handled?
By calendar month, not by 30 days. Adding one month to 15 March gives 15 April. Where the target month is shorter, the result is clamped to its last day — 31 January plus a month gives 28 or 29 February.
Can I go backwards?
Yes. Switch the operation to Subtract to find a date in the past.
Does it show the day of the week?
Yes, which is often the point — it tells you immediately whether a deadline lands on a weekend.