To find the number of days between two dates, count the calendar days from the start date to the end date, not counting the start day (the standard "difference"). Add 1 if you want to count both the first and last day, as for a hotel stay counted in days or an event that runs through the end date. From November 10, 2026 to December 25, 2026 is 45 days (6 weeks 3 days), including 33 weekdays.
Switch to "Add or subtract" to find a date a set number of days, business days, weeks, months or years away, such as 90 days from today.
How to use the date difference calculator (days between dates)
- Choose "Count days between two dates" or "Add or subtract from a date".
- Pick the start date (today by default) and the end date, or the amount and unit to add.
- Decide whether to include the end date in the count.
- Read the total days, weeks, the years-months-days breakdown and the number of weekdays.
Formula
All arithmetic is done on calendar dates (no time of day), so daylight-saving changes don't shift the count. Leap days follow the Gregorian rule.
Worked example
How many days from November 10, 2026 to December 25, 2026?
- Rest of November: 30 − 10 = 20 days.
- Plus 25 days of December = 45 days = 6 weeks 3 days = 1 month 15 days.
- Weekdays (Mon–Fri) in that span: 33.
- Add 90 days to November 10, 2026: Monday, February 8, 2027.
Business days and holidays
The weekday count excludes Saturdays and Sundays only. Public holidays vary by country, state and employer, so subtract any that fall in your range. Deadlines in contracts, courts and government rules may count days differently (calendar vs. business days, and whether the first or last day counts), so follow the rule that applies to you.
Month arithmetic has an edge case: one month after January 31 is February 28 (or 29 in a leap year) here, because February has no 31st. For ages, the age calculator uses the same convention. For hours between two times, use the time duration calculator (hours between two times).
Counting by hand
To count days across months yourself, add the days left in the start month, the full months in between, and the days into the end month. From March 15 to June 10: 16 days left in March, then 30 (April) + 31 (May), then 10 days in June = 87 days. Remember the month lengths (30 days hath September, April, June and November; February has 28, or 29 in a leap year).
Caveats and assumptions
- Business days exclude weekends only, not holidays.
- Legal and contractual day-counting rules vary; check the rule that applies.
Frequently asked questions
How do I calculate the number of days between two dates?
Subtract the start date from the end date. Add 1 if you want to count both the first and last day.
How many days until Christmas?
Set the start date to today and the end date to December 25. From November 10, 2026 it is 45 days.
What date is 90 days from today?
Switch to "Add or subtract", enter 90 days. From November 10, 2026 it is February 8, 2027.
Does it count weekends and holidays?
The main total counts every calendar day. The business-day line removes Saturdays and Sundays but not holidays.
How many weeks are between two dates?
Divide the number of days by 7. 45 days is 6 weeks and 3 days.
Sources
- U.S. Naval Observatory — Leap Years — Gregorian leap year rule used for day counts
This calculator gives estimates for planning and education. Check measurements, local codes, supplier specs and your school's official policy before relying on a result. See our disclaimer and how we build and check calculators.