Duration Between Two Dates

Calculate the exact difference between two dates — in years, months, and days — and see totals in weeks, days, hours, minutes and seconds. Calendar-aware math with leap years.

Pick your range

Years must be ≤ 9999. Dates are interpreted in your local timezone.

Output

Exact difference
—
Breakdown
Years: —
Months: —
Days: —
Totals
Total weeks: —
Total days: —
Total hours: —
Total minutes: —
Total seconds: —
Months vary in length; the exact Y-M-D uses calendar math. Totals are computed from the raw millisecond difference.

Duration Between Two Dates

Calculating the duration between two dates involves determining the time span in years, months, days, hours, minutes, and seconds from one date to another. This information is crucial for evaluating timelines, measuring progress, and making informed decisions.

How to calculate the date difference

  • Identify Start and End Dates: choose the two dates you want to compare (project start/end, contract period, etc.).
  • Compute the Difference: subtract the earlier date from the later date. For the exact calendar result, factor in leap years and month lengths; for totals, use the raw millisecond span.
  • Present the Result: display both — an exact “X years, Y months and Z days” plus totals in weeks/days/hours/minutes/seconds for quick reporting.

Practical applications

  • Project management: lead-time, cycle time, and milestone tracking.
  • Legal & compliance: contract durations, cooling-off periods, retention windows.
  • HR & payroll: service time, benefits eligibility, probation periods.
  • Finance & billing: subscription terms, interest accrual windows, invoice aging.
  • Education: academic terms, semester lengths, attendance audits.

Tips & best practices

  • Timezones matter: browser date inputs are interpreted in your local timezone. Stick to dates (no times) to avoid DST surprises.
  • Calendar vs. totals: “years, months, days” respects real month lengths; totals are linear (24h days).
  • Leap years: the tool accounts for 29-day Februaries automatically.
  • Copy quickly: use the Copy button to paste results into reports or spreadsheets.

Related tools

Need the reverse or adjacent conversions? Try our Age from Date, Date Converter, Milliseconds and Seconds converters.

FAQ

What’s the difference between calendar duration and total days? Calendar duration counts real months and years, while total days come from a simple millisecond difference divided by 86,400,000.

Does it handle leap years? Yes. The Y-M-D breakdown adjusts for leap years and varying month lengths.

Why can totals disagree with the calendar breakdown? Because months aren’t equal: a span like Jan 31 → Mar 1 is 1 month and 1 day, not a fixed number of 30-day months.

Can I compare future dates? Yes. The tool works for past and future ranges up to year 9999.

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