Date Add or Subtract Days
Add or subtract calendar days from a chosen date.
Try a worked example
Try a worked example
How to use this
Choose a start date, add or subtract, then a whole number of days. Calculate to find the new date.
0–100,000 whole calendar days; years 0001–9999. Weekends and holidays count.
Example input
2024-02-28 + 1
Expected result
2024-02-29
Adding 1 day to 2024-02-28 gives 2024-02-29: 2024 is a leap year.
More detail
Calendar dates are calculated in UTC. This is not a business-day or elapsed-hours calculation.
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Quick answer
Add or subtract whole calendar days from an ISO date.
The page and its assets load from the site; this operation uses your entered values only in this browser and does not send them to a calculation endpoint.
How to use it
Choose a start date, select whether to add or subtract, and enter a whole number from 0 to 100,000 calendar days. Enter 0 to keep the same date. Results outside years 0001–9999 are rejected; weekends and public holidays are not skipped.
Limits
The result must remain between years 0001 and 9999. This does not skip weekends or public holidays.
Frequently asked questions
How do I subtract days?
Choose “Subtract days” to move backward by the number of calendar days entered. The allowed value is a whole number from 0 to 100,000.
What happens if I enter 0?
The result is the same date you entered.
Can the result be outside years 0001–9999?
No. The tool reports an error if the calculated date would fall before 0001-01-01 or after 9999-12-31 instead of returning a truncated date.
Does it skip weekends or holidays?
No. It adds or subtracts calendar days, including weekends and holidays.
Sources and references
These references document the cited standard or browser API; they do not validate the tool’s output.