Add to or subtract from a date
Start from any date, add or subtract an amount of time, and get the exact date and weekday.
The date will be
November 30, 2026Monday · in 30 days
- Day of the week
- Monday
- ISO week number
- Week 49
- Day of the year
- 334
- Days from the start date
- 30
- ISO 8601
- 2026-11-30
How dates are added
Years and months are added first and keep the day of the month when it exists; otherwise the last day of the month is used. Weeks and days are then added as whole days. Subtracting works the same way backwards.
Questions and answers
What happens when I add a month to 31 January?
The result is the last day of February (28 February, or 29 in a leap year), because 31 February does not exist. The calculator always clamps to the last valid day.
Can I combine years, months, weeks and days?
Yes. Years and months are applied first, then weeks and days. This is how calendars and contracts usually count.