Add or Subtract Days from a Date

Add or subtract days, weeks, months or years to or from any date to find the resulting date and its day of the week, such as 90 days from today.

How to use the add or Subtract Days from a Date

  1. Pick the start date.
  2. Choose the add or subtract from the list.
  3. Enter the amount.
  4. Choose the unit from the list.
  5. The result updates instantly as you type. There is no button to press.
  6. Use Copy result to copy the figures, or Copy link to share a link that reopens the add or Subtract Days from a Date with the same inputs.

How it works

Deadlines, notice periods, warranties, prescriptions, visas and payment terms are often stated as a number of days, weeks or months from a starting date. This calculator finds the resulting date instantly, along with its day of the week, so you can see straight away whether it lands on a weekend.

Days and weeks are added on the real calendar, so the result automatically handles month ends and leap years: 30 days after January 15 is February 14. Months and years work differently, because months aren't all the same length. Adding a month keeps the same day number where possible (March 15 + 1 month = April 15). When the target month is shorter, the result is clamped to its last day, so January 31 + 1 month is February 28, or 29 in a leap year. This is the convention used by most spreadsheets, banks and programming libraries.

Be careful with contracts and legal deadlines: "within 30 days" and "within one month" can give different dates, and some rules exclude the start day, weekends or public holidays. For deadlines measured in business days, use the working days calculator.

Formula

Days: result = date + n Weeks: result = date + 7n Months: result = same day, n months later (or the last day of that month) Years: result = same day, n years later (Feb 29 → Feb 28)

Example

90 days after October 5, 2026 is January 3, 2027, a Sunday: 26 days to the end of October, 30 in November, 31 in December, then 3 in January. Adding 3 months to the same date instead gives January 5, 2027, two days later, because October to January spans months of 31, 30 and 31 days.

Frequently asked questions

Is the start date counted?

No. Adding 1 day to Monday gives Tuesday. If your rule says the start day counts as day 1, subtract one from the amount.

What is 1 month after January 31?

February 28, or February 29 in a leap year. When the day doesn't exist in the target month, the result is moved to that month's last day.

How do I find a date in the past?

Choose 'Subtract' to count backwards, for example to find the date 180 days ago.