Add Days Calculator
Add or subtract days, weeks, or months to any starting date to find future or past target dates.
Target date
Friday, Sep 11, 2026
2026-09-11iso date•
Fridayday of week•
+30 daysdays offset
Add or subtract any number of days to a start date to compute exact future or past calendar dates.
Worked Example
- Addition: December 25, 2026 + 10 days = Monday, January 4, 2027
- Subtraction: March 1, 2026 - 5 days = Tuesday, February 24, 2026
Frequently Asked Questions
Does this calculator handle leap years correctly?+
Yes. Date arithmetic uses standard Gregorian calendar rules, including February 29th on leap years.
Are timezone shifts avoided?+
Yes. Calculations use UTC date arithmetic to ensure the date number never shifts due to daylight saving time or local timezone offsets.
Can I subtract days as well as add days?+
Yes. Toggle the operation selector between Add (+) and Subtract (-) to calculate past dates.
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