Date & Time
Date Calculator
Add or subtract days, weeks, months, or years from any date. Includes end-of-month and leap-year edge cases.
Add or subtract from a date
Result date
Tuesday, July 27, 2027
That is a Tuesday, in 365 days.
Days from today
365
Weekend?
No
Timing
Future
ISO date
2027-07-27
Frequently Asked Questions about the Date Calculator
In what order are years, months, weeks, and days applied?
Years and months are applied first as calendar arithmetic, then weeks and days are added as fixed 7-day and 1-day offsets. So "1 month and 10 days after January 15" first moves to February 15, then adds 10 days to reach February 25. Mixing the steps in a different order would produce a different date, so the sequence matters.
What happens if I add a month to January 31?
The result is clamped to the last valid day of the target month. January 31 plus one month gives February 28 in a non-leap year, or February 29 in a leap year. The date never overflows into March.
Does this calculator handle leap years?
Yes. Adding one year to February 29 lands on February 28 in non-leap years and stays on February 29 in leap years. Day-count results that cross a leap-year boundary automatically include the extra February 29 in the total.
Can I subtract time to find a past date?
Yes. Switch the operation to subtract and the calculator works backward through the calendar, applying the same month-clamping and leap-year logic used for addition. For example, subtract 6 months from August 31 to get February 28 (or 29).
Why does the result show a different weekday than I expected?
Calendar arithmetic does not preserve weekdays. Adding one month to a Monday will rarely land on another Monday, because months contain 28-31 days rather than an exact multiple of 7. The calculator returns the correct weekday for whatever date the arithmetic produces.