Free tool · No sign-up

Date Calculator (Add or Subtract)

Pick a start date, enter a duration in years, months, weeks, and days, and choose add or subtract — this calculator returns the exact resulting date, the weekday it lands on, and the total day difference. Month math is calendar-aware (Jan 31 + 1 month clamps to the end of February instead of rolling into March). It runs entirely in your browser: free, instant, and no sign-up.

Start date

Operation

YearsMonthsWeeksDays

Pick a start date and enter a duration — years, months, weeks, or days — to see the resulting date.

Frequently asked questions

Enter the start date, type the number of days (and optionally weeks, months, or years), and choose Add. The calculator walks the calendar forward — including month lengths and leap years — and shows the exact resulting date and its weekday. Choose Subtract to go backwards instead.

Months are added calendar-aware with clamping: January 31 + 1 month gives the last day of February (Feb 28, or Feb 29 in a leap year) rather than rolling over into March 3. Years and months are applied first, then weeks and days.

Yes — fill in any mix of the four fields and they're applied together in that order (years and months first, then weeks and days), which is the convention most date calculators follow.

Yes — free, no sign-up, and everything is computed in your browser, so the dates you enter are never uploaded or stored anywhere.