Calculate the time between two calendar dates
Choose the dates and decide whether the start date should count. The breakdown distinguishes calendar days from weekdays; public holidays are not removed.
Dates are calculated as calendar dates in UTC, so daylight-saving changes do not add or remove a day.
How the date difference is calculated
For the ordinary “days between” result, subtract the start calendar date from the end calendar date. The start date is excluded: September 1 to September 2 is one day. When you select the inclusive option, both dates count: September 1 through September 2 is two days. The tool calculates each calendar date at UTC midnight to avoid a daylight-saving change producing a fractional-day error.
Worked example: an inclusive deadline
Suppose a project runs from September 1 through September 10. The dates are nine days apart, but counting both the first and final date gives ten calendar days. The first answer is useful for elapsed time; the inclusive answer is useful when each date is an occupied day. Choose the convention that matches your deadline, booking or schedule.
What the weekday result means
The weekday count includes Monday through Friday in the selected interval. It does not know your country, public holidays, school closures, company workweek or time zone. If you are planning business days, subtract the applicable holidays yourself and check whether your organization treats any weekend dates as working days. A same-day range gives zero days between dates, or one calendar day when the inclusive option is selected.
Check your counting convention
Use our date-counting guide to compare a Friday-to-Monday interval, a leap-day boundary and a same-day range. Each example explains which dates count and why weekday totals can differ from working days.
Reversed dates and limitations
If the entered end date comes before the start date, the calculator displays the absolute duration and flags the reversed order. The answer represents calendar days, not exact elapsed hours between two timestamps. It cannot account for appointment times or partial days. For a legal or contractual deadline, verify the governing counting rule, because some deadlines exclude the first day or shift when the final day falls on a non-working day.
See our worked calculator guides for examples of checking input assumptions, and our calculation standards for how we test boundary cases.