Days Between Dates Calculator
Count the days between two dates, with or without the end date, plus weeks, months and weekdays (Mon–Fri) in between. Works for past and future dates.
Calendar days
Calendar dates only, without times of day or holiday calendars. Negative results mean the end precedes the start. The weekday statistic is not an elapsed work-hours estimate.
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How this calculator works
Subtract two calendar dates to find a signed day count. Reversing the dates reverses the sign. Inclusive mode counts the endpoint as well, making an identical pair one counted day. Weekdays use the explicitly separate half-open interval [start, end), so the endpoint option does not alter that statistic.
Formula
Days = (UTC end − UTC start) / 86,400,000. Inclusive mode adds one in the direction of travel.
Assumptions & limitations
Calendar dates only, without times of day or holiday calendars. Negative results mean the end precedes the start. The weekday statistic is not an elapsed work-hours estimate.
Sources & reference material
- Date and UTC calendar methods ↗
Calendar arithmetic uses UTC date boundaries, not local elapsed hours.
Worked example
20 October to 19 November 2026 spans 30 calendar days. With the end date included the count is 31. Reversing the dates gives −30 in exclusive mode.
Useful next calculations
Choose a related task to continue with the right assumptions:
Common questions
Why does inclusive mode add a day?
The ordinary subtraction measures boundaries crossed. Including both calendar endpoints adds one counted date.
Does daylight saving change the result?
No. The calculation uses UTC calendar boundaries rather than subtracting local timestamps.
Are business days the same as weekdays?
Not always. This count removes Saturdays and Sundays, but keeps bank and public holidays.