Add calendar time or move by working days
Choose a unit that matches the task
Calendar days include every date. A week is seven calendar days. Months and years move through the calendar rather than using a fixed number of days, so one month is not always 30 days and one year is not always 365 days. Use add or subtract to choose the direction.
What happens at the end of a month
If the target month has no matching day, the result uses its last valid date. January 31 plus one month becomes February 28 in 2026 and February 29 in 2028. A single calculation uses the original date; repeating separate month additions can produce a different result after an intermediate clamp.
Business-day mode
Business-day counting is available for the days unit. It excludes the starting date, then skips Saturdays, Sundays and country-wide holidays from the selected source calendar. For a regional calendar, a custom workweek or company days off, use the main business-days calculator to inspect the interval.
Read the result with its assumptions
The day difference below the result is a calendar-day difference, even when you add months or business days. Enter an integer from 0 to 10,000. This tool does not move a calendar result away from a weekend unless business-day mode is selected.
Three different meanings of adding time
| Input | Result |
|---|---|
| January 31, 2026 + 1 month | February 28, 2026 |
| January 31, 2026 + 30 calendar days | March 2, 2026 |
| Friday July 17, 2026 + 1 business day; no holidays | Monday July 20, 2026 |
Frequently asked questions
Is the starting date day one?
No. Adding one day moves to the following date; adding zero keeps the starting date.
Why can adding a month twice differ from adding two months?
An intermediate month-end adjustment may change the starting day of the second operation. Choose the single interval that represents your task.
Are holidays used for months or years?
No. Holidays are applied only in business-day mode for the days unit.
See the rules and formulas in our calculation methodology. Found a discrepancy? Send an example for review.
Explanation reviewed October 17, 2026. Example results depend on the stated assumptions.