Calculate
Date difference and offset calculator
Find the number of days between two calendar dates, or add and subtract days from a starting date. Calculations use calendar dates, not time zones.
Days between dates
7 days
Add or subtract days
New date
September 21, 2026
How to use
Use the first panel for a day count between two dates. Use the second panel to move a date forward or backward by a whole number of days.
Questions
- Does the calculator include the end date?
- The difference is the number of midnights between the two dates. 1 January to 2 January is 1 day.
- Why not use timestamps?
- Calendar-day math avoids off-by-one errors from time zones and daylight saving. You pick dates, not clock times.