Date
Add or subtract days, weeks, months, and years from a date
How to use Date
- 1Enter a start date and choose add or subtract.
- 2Specify the number of days, weeks, months, or years to shift.
- 3Read the resulting date, plus the count of days between two dates if comparing.
Working with calendar dates
Result = Start date +/- interval, with month-length and leap-year rules appliedDate arithmetic must handle months of different lengths and leap years, so the calculator counts actual calendar days rather than assuming 30-day months.
When subtracting, you get both the target date and the exact number of days elapsed, useful for deadlines and age.
Frequently asked questions
Does it count the start day?
It counts whole intervals; for days between it returns the difference without double-counting endpoints.
How are leap years handled?
Years divisible by 4 are leap, except centuries not divisible by 400.
Can I find a due date?
Add the required number of days to the start date to get the deadline.