Lifestyle & Sleep
Date Calculator
Deadlines, contracts, holidays, countdowns, measure the exact gap between any two dates, in days, weeks, and business days.
Date calculators find the duration between two dates or add days to a date. For example, from January 1 to January 31 is 30 days. Business-day counts optionally exclude weekends and holidays. Use the result as a planning estimate; individual circumstances vary.
Exact day counts between dates.
Business days exclude weekends.
Weeks and remaining days included.
Calculate Your Date
Duration
What Is Date?
Date arithmetic underpins deadlines, warranties, billing cycles, and countdowns. The calculator measures the gap in calendar days, then re-expresses it in weeks and business days.
Business-day counts exclude weekends; public holidays vary by country and are noted separately where relevant.
How It Is Calculated
Duration = end date − start date (calendar days)
Example: Example: Jan 1 → Aug 17, 2026 = 228 days (32 weeks + 4 days)
Quick references
| Span | Days |
|---|---|
| 1 week | 7 |
| 30-day month | 30 |
| Calendar year | 365 |
| Leap year | 366 |
| Jan 1 → Aug 17 (2026) | 228 |
Limitations
- Holiday calendars differ by country, add your own adjustments.
- Day-count conventions in finance (30/360 etc.) differ from calendar counting.
Sources & Review
References used for this calculator’s formulas and thresholds:
Date FAQ
How do I count days between dates?
Subtract the earlier date from the later one and divide by 86,400 seconds, or let this calculator do exactly that.
Do you include both end dates?
This calculator counts calendar days between the two dates, exclusive of the start day, standard for durations.
How many business days are in a year?
260–262 (52 weeks × 5 days), minus public holidays.
What is the 30/360 convention?
A finance convention treating every month as 30 days, used in bond and loan math, different from calendar counting.
Important disclaimer: Results are educational estimates, not a substitute for professional advice. Review your numbers with a qualified advisor before acting on them.