Formula
Both dates are read as calendar dates. The result is the number of midnights between them:
Days = end date − start date
The start date is not counted as a full day. January 1 to January 31 is 30 days.
Assumptions
- Dates are calendar dates, without a time of day.
- The end date is on or after the start date.
- Weeks are groups of 7 days, with a remainder.
Worked example
January 1, 2026 to January 31, 2026 is 30 days, which is 4 weeks and 2 days.
Input definitions
- Start date
- The first calendar date. It is not included in the day count.
- End date
- The later calendar date.
Limitations
This does not count business days, holidays, or time zones. The same calendar date in two zones is still one date here.
Questions
Is the end date included?
The count is the gap between the dates. From the 1st to the 2nd is 1 day.
Can both dates be the same?
Yes. The difference is 0 days.