Add to or subtract from a date
Start from any date and move by days, weeks, months, or years. Useful for deadlines ("90 days from signing"), notice periods, and return windows.
Pick a start date and an amount.
How month math is handled
Days and weeks move by calendar days. Months and years move the calendar month and clamp to real month ends: January 31 plus one month lands on the last day of February (the 28th, or the 29th in a leap year). The tool uses this rule consistently; a particular contract or billing system may use a different rule.
Worked examples
- January 1, 2026 plus 30 days is January 31, 2026. The starting date counts as day zero.
- January 31, 2026 plus one month is February 28, 2026.
- March 1, 2024 minus one day is February 29, 2024, because 2024 is a leap year.
- February 29, 2024 plus one year is February 28, 2025.
A month is not a fixed number of days. Adding two months in one calculation can also differ from adding one month twice: January 31 plus two months is March 31, while the intermediate February result can clamp to the 28th or 29th. Use the original starting date when you want the original day of the month preserved.
Choose the right kind of interval
Weekends and holidays are included, and the result does not move automatically to the next working day. One week means seven calendar days. Daylight saving changes do not turn a calendar day into an extra date here; this tool does not measure elapsed hours. For the gap between two known dates, use days between dates. Check any deadline's own counting rules before relying on the result.