Formula
The day gap does not count the start as an extra day. Weeks divide that gap by 7:
Weeks = (end date − start date) / 7
The date difference page shows whole weeks and leftover days. This page keeps the fraction.
Assumptions
- The end is on or after the start.
- A week is 7 days.
Worked example
January 1, 2026 to January 31, 2026 is 4.29 weeks.
Input definitions
- Week
- Seven calendar days, including a fraction.
Limitations
This is not a count of Mondays or work weeks.
Questions
Why not a whole number of weeks?
Thirty days is 4 weeks and 2 days, which is 4.29 weeks.
Does the start date count?
No. The gap is the same one the date difference page uses.