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Add or subtract days from a date

Find the date that is a number of days, weeks, months or years away.

  • Runs in your browser
  • No sign-up

Then you can

How to add or subtract days from a date

  1. Enter the start date as YYYY-MM-DD.
  2. Choose Add or Subtract, then type the amount.
  3. Pick the unit: days, weeks, months or years.
  4. Turn on Skip weekends if you need business days.

The answer shows the new date with its weekday, the ISO form for spreadsheets, and the gap in days and weeks.

How it works

Days and weeks move the calendar forward by exact day counts, so adding 45 days to 31 January 2026 gives 17 March 2026. Months and years are different. They keep the day number and clamp it to the last day of shorter months, so 31 January plus 1 month is 28 February, and 29 February 2028 plus 1 year is 28 February 2029.

With Skip weekends, the tool steps one day at a time and counts only Monday to Friday. A week counts as 5 business days.

Worked example

A supplier promises delivery within 30 days of an order placed on Monday 16 March 2026.

  • Calendar days: 16 March plus 30 days is 15 April 2026, a Wednesday.
  • Business days: 30 business days is exactly six working weeks, so the date lands on Monday 27 April 2026.

If the order were due in 2 months, the result would be 16 May 2026. Which unit to pick depends on how the contract is written, so read the wording carefully.

Typical uses

  • Due dates: invoices with 30, 45 or 60 day terms.
  • Pregnancy and project planning: 280 days from a start date, or 12 weeks from a kickoff.
  • Returns and warranties: the last day to return something bought today.
  • Looking back: subtract 90 days to find the start of a quarter or a notice period.

To count days between two known dates, use the date difference calculator. To find someone’s exact age, use the age calculator. Converting a duration? The days to hours converter turns 3 days into 72 hours. All calculations stay on your device.

Questions

How do I add 90 days to a date?

Enter the start date, choose Add, type 90 and pick Days. The result shows the date, the weekday and the number of weeks between.

What is 31 January plus 1 month?

28 February in a common year or 29 February in a leap year. When the target month is shorter, the date moves to its last day.

Can I skip weekends?

Yes. Turn on Skip weekends to add business days. 10 business days from a Monday is the Monday two weeks later.

Can I subtract days to find a date in the past?

Yes. Choose Subtract. It works for due dates, notice periods and looking back from a deadline.

Are public holidays excluded?

No. Only Saturdays and Sundays are skipped, because holidays differ by country and year.

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