How the calculator counts
This calculator counts the number of calendar-day boundaries from the start date to the end date. It treats the start date as day zero and does not add an extra day for inclusive counting.
Worked example
From 2026-01-01 to 2026-03-01 there are 59 days. That equals 8 full weeks and 3 extra days, or about 8.43 weeks.
Inclusive vs exclusive dates
If you need to count both the start and end dates as included days, add one day to the result. For example, a Monday-to-Monday span is 7 elapsed days, but 8 inclusive calendar dates if both Mondays are counted.
Calendar weeks are different
This calculator returns elapsed weeks between two dates. It does not count ISO calendar week numbers, payroll weeks, academic weeks or business weeks.
Common mistakes
- Expecting inclusive date counting when the question is elapsed time.
- Rounding partial weeks without showing leftover days.
- Using this result for deadlines that depend on local legal or business-day rules.
- Mixing date-only calculations with time zones or time-of-day cutoffs.
When this method does not fit
Use a business day calculator for workday deadlines, a time duration calculator for hours and minutes, or a date calculator when adding or subtracting a specific number of days.
Last reviewed: 2026-05-17