Date Range Calculator
Easily calculate the duration (days, weeks, months, years) between two dates, optionally including the end date or restricting to work days.
Duration summary
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Target date
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How to Use This Calculator
Choose a mode to either measure the span between two calendar dates or advance/regress from a reference date. Duration mode shows the total days plus an average week/month/year breakdown, while the Add/Subtract mode reveals the precise target date after shifting by years, months, and days.
Adjust the optional toggles in duration mode to include the end date or limit counting to weekdays only. The interface validates your entries and keeps all sums deterministic so you can rely on consistent rounding.
Why use this calculator?
- Instantly see a duration breakdown in years, months, and days.
- Exclude weekends to understand work-day pacing with the work days toggle.
- Add or subtract time from any reference date with a single interface.
- Accessible, mobile-first layout works on every device.
Methodology
The calculator converts calendar dates to midnight timestamps and compares milliseconds to deliver the total-day count. When the end date is included, we add one day so the range stays inclusive. Work day mode walks the range day-by-day to skip Saturdays and Sundays.
Add/Subtract mode applies years, months, and days sequentially using the JavaScript Date API so that month boundaries and leap years are handled consistently.
- Total days are rounded to the nearest whole number unless you request the work days tally.
- Weeks, months, and years use standard averages (52 weeks, 365.25 days) for smooth comparability.
- All results are deterministic and sanitize user input to avoid NaN or Infinity.
Numbers are estimates intended for planning and not a substitute for official calendars or legal advice.
Full original guide (expanded)
Audit: Complete · Verified on 2026-01-19 by Ugo Candido.
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