Date Difference Calculator
Calculate the exact number of days, weeks, months, years, and business days between two dates.
Equivalent to 1 month (4 full weeks).
20
Mon – Fri10
Sat & SunDid this calculation save you time?
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What Is a Date Difference Calculator?
A date difference calculator computes the temporal duration between two calendar dates. It provides breakdowns of total calendar days, full weeks, months, calendar years, and working business days (excluding Saturdays and Sundays).
How to Use This Calculator
- Select the Start Date.
- Select the End Date.
- Toggle "Include End Date" if your project or rental duration counts both boundaries.
- Review the business days, weekend days, and full year/month/day duration.
Date Difference Computation
\Delta t = \frac{t_2 - t_1}{86,400,000 \text{ ms/day}}Universal Time Coordinated (UTC) midnight timestamps are subtracted to avoid daylight saving shifts, and days of the week are evaluated to isolate Monday through Friday business days.
Worked Example
Scenario: Find working days between October 1, 2026 and October 15, 2026.
Total span: 14 calendar days.
Weekend days: 4 days (2 Saturdays, 2 Sundays).
Business days: 10 working days.
Tips & Key Notes
- When calculating contract periods, check whether the contract terms define days as calendar days or working business days.
- Turn on "Include End Date" when calculating hotel stays vs. inclusive event dates.
Frequently Asked Questions
Are public holidays excluded from business days?
This calculator standardizes business days as Monday through Friday. Because national holidays differ across jurisdictions and companies, federal holidays are not automatically deducted.
Does the calculator work across centuries?
Yes, the underlying calendar system uses Gregorian calendar standards for past and future centuries.
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