Add or subtract days, weeks, months or years from any calendar date and see the resulting weekday and date.
Calculations happen locally. We do not send your values to our server.
14 days after December 20, 2026 is January 3, 2027, and 6 weeks after September 15, 2026 is October 27, 2026. Adding 1 month to January 31, 2026 gives February 28, because February has no 31st.
Days and weeks move along the calendar one day at a time, so weekends, holidays and year boundaries are simply crossed. Months and years keep the same day of the month when the destination month is long enough, and otherwise clamp the result to that month’s final day.
Dates are handled as local calendar days without clock times, so daylight saving changes never shift the answer. Legal and financial deadlines may count the starting day differently, or move a deadline that lands on a weekend or holiday to the next working day, so confirm the counting rule before relying on the date.
Choose a starting date, an amount, a unit and whether to add or subtract. Days and weeks count calendar days one by one, so 14 days after December 20, 2026 is January 3, 2027, crossing into the new year automatically, and 6 weeks after September 15, 2026 is October 27, 2026. Weekends and holidays are included in the count. For deadlines that skip weekends, use the Business Days Calculator to check how many working days a period contains.
Adding months keeps the same day of the month unless the destination month is shorter. One month after January 31, 2026 is February 28, because February has no 31st. Two months after January 31 is March 31, but adding one month twice gives a different answer: February 28 plus one month is March 28. Subtracting works the same way, so one month before March 31, 2026 is February 28. When a contract says “end of month”, check the actual last day rather than adding months.
A February 29 moved by a year lands on February 28 in a non-leap year, so February 29, 2024 plus one year is February 28, 2025. Dates are handled as local calendar days without clock times, so daylight saving changes never shift the answer. Legal and financial deadlines may count the starting day differently or move a deadline that falls on a weekend or holiday to the next working day, so confirm the counting rule that applies before relying on the date.
| Input | Result |
|---|---|
2026-01-31 +1 mo | 2026-02-28 |
2026-01-31 +2 mo | 2026-03-31 |
2026-02-28 +1 mo | 2026-03-28 |
2024-02-29 +1 y | 2025-02-28 |
2026-03-31 −1 mo | 2026-02-28 |
2026-12-20 +14 d | 2027-01-03 |
2026-09-15 +6 wk | 2026-10-27 |
Because each step clamps separately. 2 months after January 31, 2026 is March 31, but January 31 plus 1 month is February 28, and February 28 plus 1 month is March 28. Subtracting behaves the same way: 1 month before March 31, 2026 is February 28. When a contract says “end of month”, use the actual last day instead of adding months.
It clamps to February 28 in a non-leap year, so February 29, 2024 plus 1 year is February 28, 2025. Four years later the date exists again. Anniversaries, renewals and age milestones that fall on February 29 are handled differently by different rules, so check which one applies to your case.
Yes, every calendar day counts, including Saturdays, Sundays and public holidays. That is why 14 days after December 20, 2026 lands on January 3, 2027 despite the holiday season. For a deadline expressed in working days, use the Business Days Calculator instead.
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