Date Difference Calculator
Find the number of days, weeks, months and years between two dates, including business days excluding weekends.
Inputs
Formula
- ฮdays = (tโ โ tโ) / 86 400 000
- Business days = ฮdays โ weekend days in the interval
The difference between two dates is computed from epoch milliseconds, which removes month-length and leap-year ambiguity. Business days are then obtained by walking the interval and skipping Saturdays and Sundays โ the convention used for payment terms and project schedules.
Step-by-step calculation
Start
tโ
Thu Jan 01 2026
End
tโ
Thu Dec 31 2026
Difference
(tโ โ tโ) / 86 400 000
364 days
Business days
walk interval, skip Sat/Sun
260 days
Worked example
- 1 January 2026 to 31 December 2026, end day not counted.
- ฮ = 364 days = 52 weeks 0 days โ 11 months 30 days.
- Business days = 260.
Tips
- Contracts usually mean 'clear days' โ the start day is excluded and the end day included. Toggle the switch to match.
- Business days here exclude weekends only; public holidays vary by country and must be deducted separately.
Frequently asked questions
Does this include the end date?
Only if you choose to count the end day. By default the result is the plain difference, so 1 Jan to 2 Jan is 1 day.
Are public holidays excluded?
No. Only Saturdays and Sundays are removed from the business-day count, because holidays differ by country and state.
Can the end date be earlier than the start?
Yes โ the calculator reports the absolute difference.
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