Add Days to Date Calculator
Add or subtract calendar days from a start date, then see the resulting date, weekday, ISO week, day of year and month calendar.
Add or Subtract Days Calculator
Date details
Result month calendar
How it was calculated
Add or subtract calendar days
English date-calculator intent is usually practical: choose a start date, add or subtract a number of calendar days, and get the future or past date with the weekday.
D_result is the calculated date, D_start is the start date, and n is the number of calendar days to add or subtract.
Calendar days, not business days
- Month-end transitions are handled by the calendar.
- Leap years and February 29 are included when the date range crosses them.
- The result includes weekday, ISO week, day of year and a mini calendar for quick planning.
Frequently Asked Questions
Sources and References
- DateMDN Web Docs
- Representing dates and timesMDN Web Docs
- Gregorian calendarBritannica
- SI Units: TimeNIST
- Date Calculatortimeanddate.com
Calculations are based on the listed reference sources. Links open in a new tab.
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