Add or Subtract Days Calculator
Add or subtract a number of days from a date and get the resulting date along with the day of the week it falls on — useful for calculating deadlines, due dates, or future and past dates.
How is it calculated?
Resulting date = the date you enter + (or −) the number of days given, using real calendar arithmetic (JavaScript Date with UTC): month and year rollovers, including leap years, are resolved automatically.
Examples
Add 30 days to January 1, 2026
January 31, 2026 (Saturday).
Subtract 45 days from March 15, 2026
January 29, 2026 (Thursday).
Add 365 days in a leap year
December 31, 2028 (2028 is a leap year, so 365 days don't quite complete the full year).
Common use cases
- Calculate a deadline's due date (for example, "30 days from signing").
- Find out what day of the week a future date falls on.
- Calculate a past date ("90 days ago").
- Plan reminders or follow-ups X days out.