How days between dates are counted
Each date is converted to a day number and the two are subtracted. Because the calculation uses calendar dates rather than clock times, daylight saving changes cannot introduce off-by-one errors.
Days = End date − Start date (+ 1 if the end date is included)
Example: From January 1, 2026 to December 25, 2026 there are 358 days — 51 weeks and 1 day, or 11 months and 24 days. Including the end date, the count is 359 days.
Days in each month
| 31 days | 30 days | 28 or 29 days |
|---|---|---|
| Jan, Mar, May, Jul, Aug, Oct, Dec | Apr, Jun, Sep, Nov | Feb |
Common uses: countdowns to holidays, trips and weddings; deadlines and notice periods; loan and rental periods; tracking streaks and anniversaries.
Frequently asked questions
How many days are between two dates?
Subtract the earlier date from the later one. The calculator counts calendar days and accounts for leap years and different month lengths automatically.
Should I include the end date?
By default the result counts the days from the start date up to, but not including, the end date — the same way you would count nights in a hotel. Tick “include end date” to count both the first and the last day, for example for the length of an event or a contract period.
How many days are in a year?
A common year has 365 days and a leap year 366. Leap years occur every 4 years, except years divisible by 100 that are not divisible by 400. So 2000 was a leap year but 1900 was not.
How do I count only working days?
Use the business days calculator, which excludes weekends and, optionally, U.S. federal holidays.