Add or Subtract Days from a Date
Move a date forward or back by days, weeks, months, and years.
Start date and amount
Fill in any combination of units; empty fields count as zero.
Years and months are applied first, then weeks and days. Month ends are explained below.
How to use this calculator
- 1
Pick the start date. Use the date picker or type it.
- 2
Choose Add or Subtract. Then enter years, months, weeks and days in any combination.
- 3
Read the new date. The weekday, ISO week and distance from the start are shown too.
Example
October 20, 2026 plus 1 month and 12 days is Wednesday, December 2, 2026: November 20, then 12 more days.
January 31, 2026 plus 1 month is February 28, 2026, because February has no 31st.
How it is calculated
Order of operations. Years and months are added (or subtracted) first, as calendar units; weeks and days are then applied as exact day counts. Adding 1 month and 12 days to October 20 gives November 20, then December 2.
End-of-month rule. If the day does not exist in the target month, the result is the last day of that month: January 31 + 1 month = February 28 (February 29 in a leap year), and March 31 − 1 month = February 28. A note appears under the result whenever this happens. Adding a year to February 29 gives February 28 in common years.
Only calendar dates are involved, so daylight saving time and time zones have no effect.
Questions
Is adding 30 days the same as adding 1 month?
No. A month is a calendar unit with 28 to 31 days, while 30 days is an exact count. January 31 plus 1 month is February 28, but plus 30 days is March 2 (in 2026).