Add or subtract years, months, weeks and days from a base date.
- Input: 2026-01-31, add 1 month, all other inputs 0, business-day option off
- Result: 2026-03-03. The nonexistent February date overflows into March; it is not clamped to the end of February.
- Input: 2024-02-29, add 1 year, all other inputs 0, business-day option off
- Result: 2025-03-01. February 29 overflows into March in a non-leap year.
- Input: 2026-10-23, add 1 week, all other inputs 0, business-day option on
- Result: 2026-10-30. One week counts as five Monday–Friday days.
What should I check?
Month-end calculations retain JavaScript date overflow behavior; check the resulting date.
In what order are durations applied?
Ordinary mode applies years, then months, then weeks and days, using JavaScript UTC date overflow. It does not clamp to the last day of a month; check the resulting date.
What does the business-day option use?
It counts weeks × 5 plus days, skipping Saturday/Sunday. The start date is not counted; years and months are ignored and public holidays are not excluded. Use the separate business-day target tool for other weekend rules.