Date Difference Calculator
Calculate the exact number of days, working days, weeks, and months between two dates.
About Calculator
The Date Difference Calculator computes the exact number of calendar days, working days (Mon–Fri), full weeks, and approximate months between any two dates. This is useful for project planning, contract duration checks, and countdown tracking.
The formula is straightforward: the total number of days equals the absolute difference between the two date timestamps divided by 86 400 000 (milliseconds per day). Working days exclude Saturdays and Sundays by iterating through each day in the range.
For legal or HR contexts, be aware that different jurisdictions count "inclusive" vs "exclusive" end dates. Toggle the "Include end day" option to add +1 day if you need the end date counted as a full day.
Frequently Asked Questions (FAQ)
How are working days calculated?
Working days include only Monday through Friday. Public holidays are not excluded automatically — only weekends are removed from the count.
Does the calculator account for leap years?
Yes. The calculator uses native JavaScript Date objects, which correctly handle leap years (Feb 29) and varying month lengths.
What does "Include end day" mean?
By default, the calculator counts from the start date up to but not including the end date. Enabling this option adds one extra day so both the start and end dates are fully counted.
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