How to use
- Pick a start date and an end date — the number of days between them appears right away. The Today button next to the end date fills in today’s date.
- Turn on Include the end date when both the first and the last day should count, such as for a vacation or an event. The result grows by one day.
- The breakdown below shows the same span in weeks, months and years, plus the number of weekdays.
How it is calculated
| Item | Method | Example (Jan 1 → Oct 5, 2026) |
|---|---|---|
| Days | End date − start date | 277 days |
| Weeks + days | Days ÷ 7, quotient and remainder | 39 wk 4 d |
| Months + days | Full months (same day of month reached) + leftover days | 9 mo 4 d |
| Years + months + days | The same method used to state someone’s age | 0 y 9 mo 4 d |
| Weekdays | Mondays to Fridays inside the range | 197 days |
By default the end date is not included, so January 1 to December 31 is 364 days. With the end date included it becomes 365 days, exactly one year.
Things to keep in mind
- Public holidays are not subtracted. The weekday count removes Saturdays and Sundays only, so Thanksgiving, Christmas or bank holidays still count as working days.
- Contracts, notice periods and legal deadlines may follow their own counting rules (for example, excluding the first day). Check the rule that applies to you.
- To find the date N days or months from now, use the date add calculator. For a countdown, try the D-Day calculator.
FAQ
Why is January 31 to February 28 not one month?
A month is counted when the same day of the month comes around again. February has no 31st, so the tool reports 0 months and 28 days. On March 1 it becomes 1 month and 1 day.
Should I include the end date?
Leave it off for questions like “how many days until” or “how many days since”. Turn it on when you count both ends, like the number of days you will be away on a trip that starts Monday and ends Friday (5 days).
Is anything sent to a server?
No. All calculations run in your browser.