How this date duration calculator works
The calculator compares the two calendar dates directly, then adds one day only when include end date is turned on. It does not use elapsed hours between local midnights, so daylight saving changes should not affect the count.
Inclusive vs exclusive date counting
Exclusive counting measures the gap between dates. Inclusive counting counts both the start date and the end date, which is useful for some travel, rental or project-period questions.
Calendar days vs business days
Calendar days include weekends and holidays. If weekends or custom excluded dates matter, use a business-day calculator instead of this calendar-day span.
What this tool does not include
This tool does not count business days, include a public holiday database, convert time zones, calculate payroll periods or provide legal deadline advice.
Key terms and assumptionsShort notes about inclusive counting, reversed dates, approximate months and business-day exclusions.
- Calendar days
- The result counts dates on the calendar, not elapsed clock hours or business days.
- End date setting
- Exclusive mode counts the gap between dates. Inclusive mode counts both the start and end dates.
- Reversed dates
- Reversed ranges warn by default. The advanced option shows the duration as a negative number.
- Month estimate
- Approximate months use the average Gregorian month length. The calendar breakdown is better for whole years, months and days.
- No holiday logic
- This calculator does not exclude weekends, public holidays or custom business-day rules.
Guides and methodology
Choose the right date or time tool for date spans, business days, time durations and schedule questions.
Related calculators and tools
Browse the Date & Time tools hub for related Date & Time tools.
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FAQs
Does the calculator include the end date?
By default it counts the gap between dates. Turn on include end date when both dates should be counted.
What happens if both dates are the same?
The exclusive count is 0 calendar days. The inclusive count is 1 calendar day.
Does this count business days?
No. Use the Business Days Calculator when weekends or custom excluded dates matter.
Are leap years included?
Yes. The calculator uses calendar date math so February 29 is counted correctly.
Why is the month result approximate?
Months have different lengths, so total days is the main result. The month estimate is supporting context only.
Does daylight saving affect the result?
It should not. The tool compares calendar dates rather than elapsed clock hours.
Can I enter reversed dates?
Yes. By default the calculator warns and shows the absolute span. Enable reversed dates to show a negative duration.