Add or subtract time from any date
Use this date add and subtract calculator to move a starting date forward or backward by a specific number of days, weeks, months or years. The result updates instantly and includes the day of the week, so it is useful for deadlines, project schedules, renewal dates, travel plans and personal milestones.
How to calculate a future or past date
Choose your starting date, select Add or Subtract, enter the amount and choose the unit. For example, adding 45 days to a contract date gives you the exact calendar date of the deadline. Subtracting 12 weeks from an event date helps you find when preparation should begin.
Starting date ± number of days, weeks, months or years = result dateThe calculator applies real calendar rules, including different month lengths and leap years.Days, weeks, months and years behave differently
A week is always seven days, but calendar months contain 28, 29, 30 or 31 days. Adding one month therefore does not mean adding a fixed number of days. The tool uses calendar-based date arithmetic so the answer stays meaningful when the starting day is near the end of a month.
Common ways to use this date calculator
- Find a payment, delivery or application deadline.
- Calculate a follow-up date after a fixed waiting period.
- Work backward from a launch, exam, wedding or travel date.
- Check the date of a warranty, subscription or contract renewal.
- Find the weekday for a future or historical date.
Frequently asked questions
Does the calculator include weekends?
Yes. This tool uses calendar days, so Saturdays, Sundays and public holidays are included. To exclude weekends, use the business days calculator.
What happens when I add months to the end of a month?
The calculation follows calendar rules and returns a valid date in the destination month. This avoids creating impossible dates such as February 30.
Can I calculate a date in the past?
Yes. Select Subtract and enter the number of days, weeks, months or years you want to move backward.