Add or Subtract Days From a Date
Start from any date and add or subtract days, weeks, months or years. Handy for due dates, deadlines, contracts and planning.
Common uses
- Payment terms: an invoice dated today with Net 30 terms is due Saturday, October 24, 2026.
- Notice periods: subtract days from a leaving date to find when to hand in notice.
- Pregnancy and health: add 280 days (40 weeks) to the first day of the last period to estimate a due date. Always check with a doctor.
- Warranties and returns: add 1 year or 90 days to a purchase date.
Frequently asked questions
How do I add days to a date?
Choose a start date, keep “Add” selected, enter the number and pick the unit: days, weeks, months or years. The new date shows instantly.
What happens when I add a month to January 31?
February has no 31st, so the calculator uses the last day of February: the 28th, or the 29th in a leap year. The same rule applies to any month-end date.
Can I subtract business days?
Yes. Set the unit to Days, choose “Subtract” and tick “Business days only”. Weekends are skipped when counting backwards.