Add or Subtract Days, Weeks, Months, Years
Local ProcessingAdd or subtract days, weeks, months or years from a date.
How It Works & Processing Standards
Add or subtract days, weeks, months or years from a date.
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Current Limits
- Maximum input length: 100,000 characters
Choose add or subtract N days, or add N weeks, months or years under "Task". Adding a month to 31 January gives 28 February (29 in a leap year), and the tool tells you it adjusted.
What You Can Do
- N days or weeks
- Moves by exactly that many days; negative numbers subtract.
- N months or years
- Moves on the calendar and clamps missing dates to month end.
- Result details
- Weekday, day of year and ISO week.
How to Use Add or Subtract Days, Weeks, Months, Years
- 1Choose a taskPick the unit to add or subtract.
- 2Enter date and amountThe base date and how many.
- 3Read the resultSee the result date and weekday.
Examples
100 days later
Input: 2026-01-01 + 100 days
Result: 2026-04-11 (Saturday)
One day earlier
Input: 2026-03-01 − 1 day
Result: 2026-02-28 (Saturday)
A month from month end
Input: 2026-01-31 + 1 month
Result: 2026-02-28 (clamped to the last day of the month)
A year from a leap day
Input: 2024-02-29 + 1 year
Result: 2025-02-28 (Friday)
Common Use Cases
- Finding anniversaries such as 100 or 1000 days
- Working out contract expiry or warranty end dates
- Checking the date N months after a payment
Frequently Asked Questions (FAQ)
What if day one is the first day?
If the start date counts as day 1, day 100 is 99 days later, so add 99.