Date Calculator
Add or subtract a number of days, weeks, months, or years from any starting date to find the resulting date — useful for deadlines, due dates, and planning.
Show solution steps
Formula
The calculator takes your start date and applies the chosen offset, correctly handling month-length differences and leap years (e.g. adding 1 month to 31 January lands on the last valid day of February).
Worked Example
Adding 30 days to 1 January 2026 gives 31 January 2026. Subtracting 1 year from 12 July 2026 gives 12 July 2025.
How to Use
- Enter your start date.
- Choose Add or Subtract.
- Enter the amount and unit (days, weeks, months, or years).
- Read the resulting date instantly.
Frequently Asked Questions
How are months handled when day counts differ?
Adding or subtracting months shifts the calendar month while keeping the same day-of-month where possible; if that day doesn't exist in the target month (e.g. 31st in a 30-day month), it rolls to the nearest valid date.
Can I use this to count days until a deadline?
Yes u2014 set the start date to today and add the number of days remaining, or use it in reverse to check what date falls a certain number of days before an event.
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