Date Duration Calculator
Quick Dates
Result Summary
How the result is calculated
Dec 31, 2025 − Jan 1, 2025 = 364 days
Date Range
364 days
How Many Days Are Between Two Dates?
Enter a start date and an end date above. The calculator determines the number of calendar days between them using two standard methods:
For example, from July 1 to July 5, the elapsed duration is 4 days (July 5 − July 1). If you turn on Include end date, both July 1 and July 5 are counted, giving 5 inclusive days.
What Does This Date Duration Calculator Calculate?
This calculator finds the duration between two calendar dates and can show the result in days, weeks, months, years, hours, minutes and seconds. It can also count business days when that option is enabled.
- Days: Total calendar days between the dates.
- Weeks: The duration expressed in weeks.
- Months and years: Calendar-based duration between the selected dates.
- Hours, minutes and seconds: Equivalent duration based on the calculated days.
- Business days: Weekdays counted, weekends excluded.
How to Use the Date Duration Calculator
- Select the Start Date.
- Select the End Date.
- Turn on Include end date if both dates should be counted.
- Review the result. The primary number is Total Calendar Days.
- Use ⇄ to swap dates if they are reversed.
Inclusive vs. Exclusive Date Counting
Standard elapsed counting measures the time from the start date to the end date. Inclusive counting includes both the start date and the end date.
| Dates | Standard | Inclusive |
|---|---|---|
| July 1 to July 5 | 4 days | 5 days |
| January 1 to January 1 | 0 days | 1 day |
Leap Years and Date Duration
Date durations can cross leap years, which contain 366 days instead of 365 because February has 29 days instead of 28. The calculator uses exact calendar dates when determining durations, automatically accounting for February 29 whenever it falls within the selected date range.
Calendar Days vs. Business Days
Calendar days count every consecutive day in the selected date range, including Saturdays and Sundays. In contrast, the calculator's business-day count includes weekdays only (Monday through Friday) and excludes Saturdays and Sundays. Public holidays are not excluded by this calculator, as statutory holiday schedules vary widely by country, state, and organization.
Date Duration Examples
Full calendar year (2025)
January 1, 2025 to December 31, 2025
Elapsed: 364 days
Inclusive: 365 days (full common year)
Consecutive year milestone
January 1, 2025 to January 1, 2026
Elapsed: 365 days (exactly 1 year)
Inclusive: 366 days
Leap year range (2024)
January 1, 2024 to December 31, 2024
Elapsed: 365 days
Inclusive: 366 days (includes February 29)
How to Calculate Days Between Dates in Excel and Google Sheets
If the start date is in A2 and the end date is in B2:
=B2-A2Simple subtraction=DAYS(B2,A2)DAYS function=DATEDIF(A2,B2,"d")DATEDIF: elapsed days=NETWORKDAYS(A2,B2)Weekdays onlyCommon Date Duration Mistakes
- Confusing elapsed days with inclusive day counting.
- Forgetting that leap years can contain 366 days.
- Assuming every month has the same number of days.
- Treating business days as the same as calendar days.
- Reversing the start and end dates.
Date Duration Calculator FAQ
How do I calculate days between two dates?
Subtract the start date from the end date to get the elapsed day count. If you need to count both the beginning and ending dates as full calendar days, add 1 (inclusive count).
What is inclusive versus exclusive counting?
Exclusive (standard elapsed) counting measures the duration between dates without counting the end date as a full day (End date − Start date). Inclusive counting includes both the start date and end date (Elapsed days + 1).
Does the calculator account for leap years?
Yes. The calculator uses exact Gregorian calendar logic. If the selected date range spans February 29 of a leap year (such as 2024 or 2028), that 366th day is automatically included in the count.
Does it count weekends?
Yes. The total calendar days count includes all Saturdays and Sundays. The calculator also breaks out business days (weekdays) and weekend days separately in the results.
Can it calculate business days?
Yes. Expand More Results to see the Business Days count, which counts Monday through Friday and excludes weekends (Saturdays and Sundays).
How are months and years calculated?
Months and years are determined using calendar-based date subtraction rather than dividing by a fixed 30 or 365 days. The calculator accounts for the varying lengths of individual months (28, 29, 30, or 31 days) to show exact elapsed years, months, and remaining days.
Why can the months and years differ from the total number of days?
Total days measure the elapsed time between two dates. The years, months, and days breakdown uses calendar units, and months have different lengths. As a result, the calendar duration does not always convert directly into the same total number of days. Use the total calendar days result when you need the exact day count.