Date and time
Add or subtract dates
Move a date forward or backward by years, months, weeks and days.
Your numbers
Both a decimal point and a comma work.
Result
2026-09-30
Resulting date
How it works
Date ± years/months, then ± weeks/days
Using the calculator
Enter: Start date · Operation · Years · Months · Weeks · Days. Calculation: Date ± years/months, then ± weeks/days.
Worked input and result
Example: Start date = 2026-01-31; Operation = Add; Years = 0; Months = 1; Weeks = 0; Days = 0. Result: Resulting date = 2026-02-28.
Understanding the result
Years and months are applied together first, then weeks and days. Missing days are clamped to month-end: January 31 + one month becomes February 28 or 29. The result uses YYYY-MM-DD.
Adding months to a date may stop at the last valid day of the target month, so 31 January plus one month is not always 28 days later. Check the final date when a deadline depends on local rules.