Days Between Dates Calculator
Pick two dates. You get the number of days between them, the same span in weeks and in calendar months, and the working days.
Sources: US Code, US Naval Observatory, Microsoft Updated
October 17, 2026 to December 25, 2026
69 days
How the days are counted
The calculator turns both dates into a day number and subtracts one from the other. That is the same as counting on a calendar from the day after the start date up to and including the end date.
days between = end date − start date
Weeks are that number divided by seven, with the remainder shown as extra days. The calendar breakdown moves forward from the start date in whole months first, then counts what is left.
To go the other way, from a number of days to a date, use the days from today calculator.
How to count the days between two dates: a worked example
From October 12, 2026 to December 25, 2026, the span the Christmas countdown covered on October 12:
- Rest of October: 31 − 12 = 19 days.
- All of November: 30 days.
- December up to the 25th: 25 days.
- 19 + 30 + 25 = 74 days, which is 10 weeks and 4 days.
- On the calendar: October 12 to December 12 is 2 months, and 13 more days reach December 25.
Days in each month
| Month | Days | Month | Days |
|---|---|---|---|
| January | 31 | July | 31 |
| February | 28, or 29 in a leap year | August | 31 |
| March | 31 | September | 30 |
| April | 30 | October | 31 |
| May | 31 | November | 30 |
| June | 30 | December | 31 |
A year is a leap year when it divides by 4, except century years, which must divide by 400: 2028 and 2000 are leap years, 2100 is not. That is the Gregorian rule as the US Naval Observatory states it.
Questions about counting the days between dates
Does the count include the start and end dates?
By default it counts the days from the start date to the end date, the way you would count nights: January 1 to January 2 is 1 day. Tick "Count the first day too" to include both dates, which is how a hotel counts days of a stay or a contract counts a notice period that starts today.
How are months and years counted?
As whole calendar months from the start date, with the leftover days after the last full month. March 15 to May 20 is 2 months and 5 days. Months have different lengths, so the same number of days can be a different number of months depending on where you start.
Can it count business days between dates?
Yes: the working days line counts Monday to Friday. Tick the holiday box to also leave out the eleven US federal holidays in 5 U.S.C. 6103, on the day they are observed: the Friday before when a holiday falls on a Saturday, the Monday after when it falls on a Sunday. The holiday dates page lists them.
How do I count the days between two dates in Excel?
Use =DAYS(end_date, start_date), which subtracts the start date from the end date and gives the same number as this calculator. For working days, =NETWORKDAYS(start_date, end_date, holidays) leaves out weekends and any holiday dates you list. It counts the start date as well as the end date, like this calculator with "Count the first day too" ticked.
Do leap years and daylight saving time affect the result?
Leap days are counted like any other day, so a span across February 29 is one day longer. Daylight saving time has no effect, because the calculator works on calendar dates, not on clock hours.
Sources
- 5 U.S.C. 6103: Holidays — the federal holidays and the weekend rule used for working days (checked October 16, 2026)
- US Naval Observatory: Leap Years — the Gregorian leap year rule (checked October 16, 2026)
- Microsoft Support: DAYS function — the Excel formula for the days between two dates (checked October 16, 2026)
- Microsoft Support: NETWORKDAYS function — the Excel formula for working days, with its worked example (checked October 16, 2026)