Add Days to a Date
October 12, 2026 plus 30 days is Wednesday, November 11, 2026.
Add or subtract days
About this calculation
Pick a start date, enter how many days to add (use a negative number to subtract), and this calculator returns the resulting date and weekday.
It handles month boundaries, leap years and year changes correctly — the cases where counting by hand goes wrong.
Useful for setting follow-up dates, working out delivery windows, projecting deadlines, or shifting a whole schedule by a fixed offset.
Frequently asked questions
Can I subtract days?
Yes. Enter a negative number, for example -45, and the calculator counts backwards from the start date.
Does it handle leap years?
Yes. February 29 is accounted for automatically, so the result stays correct across leap years.
Can I add weeks or months instead?
Not on this page. Add 7 days per week manually, and use a dedicated month calculator for month arithmetic, since calendar months are not a fixed number of days.
What is the resulting weekday based on?
The actual Gregorian calendar. Add a multiple of 7 and the weekday stays the same; anything else shifts it.