Days Between Dates Calculator
Count calendar days between two dates, optionally including the final day. Also see Monday-through-Friday weekdays, complete weeks with leftover days, and approximate months and years.
Days Between Dates Calculator tool
About the Days Between Dates Calculator
Use the calculator to compare project dates, plan trips, or check the length of a date interval. If the end is before the start, the result remains an absolute count and clearly identifies the reversed direction.
How Is Days Between Dates Calculated?
Dates are ordered chronologically for counting. By default, the earlier date is included and the later date is excluded. Turning on the end-date option includes both endpoints. Weekdays follow the same interval convention.
Days = absolute difference between UTC midnights ÷ 86,400,000 + inclusive adjustment
Inclusive adjustment = 1 when including both endpoints; otherwise 0
Complete weeks = floor(days ÷ 7); leftover days = days modulo 7
Approximate years = days ÷ 365.2425; approximate months = days ÷ (365.2425 ÷ 12)
Example
March 1, 2024, through March 4, 2024, is 3 days by default, containing 1 weekday. Including both endpoints gives 4 days and 2 weekdays.
How to Use the Days Between Dates Calculator
- Enter the start date.
- Enter the end date.
- Choose whether to include the final chronological date.
- Read the absolute calendar-day count and direction note.
- Compare weekdays and weeks plus days, keeping the approximate units separate from exact calendar counts.
Days Between Dates Calculator Examples
Crossing a leap day
February 28, 2024, to March 1, 2024, is 2 days by default or 3 days including both endpoints.
A ten-day interval
March 8, 2024, to March 18, 2024, is 10 days: 1 week and 3 days, including 6 weekdays under the default endpoint rule.
The same date
March 4, 2024, to March 4, 2024, is 0 days by default. Including both endpoints gives 1 day and 1 weekday because that date is a Monday.
Choosing an endpoint convention
Elapsed date differences and inclusive event lengths answer different questions. A Friday-to-Monday interval has three elapsed calendar days but touches four dates.
For reversed inputs, inclusion always refers to the chronologically later endpoint, not the field labeled End date.
Limits of a calendar count
This tool does not measure elapsed hours between local timestamps or calculate jurisdiction-specific business deadlines.
Use the age calculator for completed calendar years and months rather than treating the approximate conversions as exact anniversaries.
Frequently Asked Questions
Does the result include the start and end dates?
By default, it includes the earlier date but not the later date. The Include end date option counts both endpoints, adding one day.
What if the end date is before the start date?
The calculator shows the absolute interval and a direction note. Weekdays are counted from the earlier date using the same endpoint rule.
Are weekdays the same as business days?
Not necessarily. Weekdays mean Monday through Friday only. Holidays, company closures, and regional work schedules are not excluded.
Why are months and years approximate?
Months and years have varying lengths. These conversions use the Gregorian mean year of 365.2425 days rather than counting calendar anniversaries.
Does daylight saving time affect the count?
No. Dates are interpreted as UTC calendar dates, so a local 23-hour or 25-hour day does not change the count.