Add or Subtract Days from a Date
Add or subtract days, weeks, months or years to a date and see the resulting date and weekday.
Date calculator
Type a date and an amount.
Resulting date
2027-02-22
In words
Monday, 22 February 2027
2027-W08
ISO week
53
Day of the year
Private: Everything runs in this page. Nothing you type is sent anywhere or saved.
On this page
Date arithmetic examples
| Start | Change | Result |
|---|---|---|
| 2026-11-14 | add 100 days | 2027-02-22 |
| 2024-01-31 | add 1 months | 2024-02-29 |
| 2024-02-29 | add 1 years | 2025-02-28 |
| 2024-03-01 | subtract 1 days | 2024-02-29 |
| 2026-01-01 | add 52 weeks | 2026-12-31 |
Formula
days and weeks: day number + amount; months and years: same day in the new month, or its last day if it does not exist
How the date calculator works
- Step oneType the start date as YYYY-MM-DD.
- Step twoChoose Add or Subtract, type the amount and pick days, weeks, months or years.
- Step threeRead the resulting date, the weekday and the week number.
What this tool does not do
- It counts every calendar day; it does not skip weekends or holidays.
- It uses the Gregorian calendar and the years 1000 to 9999.
- It ignores time zones and times of day.
Frequently asked questions
What is 1 month after January 31?
February has no 31st, so the result is the last day of February: the 29th in a leap year, the 28th otherwise.
What is 1 year after February 29?
The next February 28, because a year later has no 29th unless it is a leap year too.
Does it skip weekends?
No. It counts every calendar day. It does not know public holidays or working days.