Date Calculator
Add or subtract days from a date, or find the number of days between two dates — one flexible tool for everyday date math.
Also covers: time and date calculator
Date Calculator
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View on AmazonHow the Date Calculator works
- Choose what you want to do: add days, subtract days, or find days between two dates.
- Enter the date(s) involved.
- Read the resulting date or day count — leap years and varying month lengths are handled automatically.
Formula / logic
Days between = (later date − earlier date) in whole days. Add/subtract = start date shifted forward or backward by N days on the calendar.
Worked example
From January 1 to December 31 in a non-leap year is 364 days. Adding 30 days to January 1 lands on January 31.
Frequently asked questions
Does it count weekends?
Yes, by default all days are counted. Switch to the Business Days Calculator to exclude weekends.
Does this account for leap years?
Yes, the calculation uses real calendar dates, so February 29 in a leap year is counted correctly.
Does 'days between' include both the start and end date?
The count reflects full days elapsed between the two dates; the start date itself counts as day zero.
Is the Date Calculator free to use?
Yes — every calculator on this site is free, with no sign-up or download required.
Does the Date Calculator work on mobile?
Yes, the layout and calculator both adapt to phone and tablet screens.