The Date Calculator measures elapsed time between any two calendar dates, breaking down the interval into total calendar days, completed seven-day weeks with remaining days, total elapsed hours, and estimated workdays.

### Duration Math & Working Day Estimation Elapsed calendar days are calculated from the absolute millisecond delta divided by standard 86,400,000-millisecond diurnal intervals: $$\text{Total Days} = \frac{|\text{End Date} - \text{Start Date}|}{86{,}400{,}000\text{ ms}}$$ $$\text{Full Weeks} = \lfloor \text{Total Days} / 7 \rfloor, \quad \text{Remaining Days} = \text{Total Days} \bmod 7$$

To give project managers and sprint planners a quick estimate of working time, the calculator also computes estimated business days using the standard 5/7 ratio ($5/7 \approx 0.7143$). For an exact weekday count that accounts for specific day-of-week starts and ends, see the dedicated Days Between Dates tool.

### Worked Duration Example Calculating the duration from January 1, 2026 to October 20, 2026: - **Total Calendar Days**: 292 days - **Weeks & Days**: 41 weeks and 5 days - **Estimated Business Days**: $\approx 292 \times (5/7) \approx 209$ business days - **Total Hours**: $292 \times 24 = 7{,}008$ hours

### Client-Side Execution All date mathematics execute locally inside your browser using the JavaScript Date API. No calendar appointments, milestone dates, or project timelines are transmitted over the network.