How to use
- Choose a start date and end date to count days.
- Check "Include both dates" if the first and last day should both count.
- To find another date, choose "Add" or "Subtract", enter an amount, and choose a unit.
How the days calculator works
By default, the day count is the later date minus the earlier date. The start date is excluded and the end date is included. October 1 to October 10, 2026 is 9 days. Including both dates adds 1, giving 10 days. If the end date is earlier than the start date, the tool swaps them.
Weeks are groups of 7 days. Months follow the calendar: the tool counts whole months from the start date, then any remaining days. Each 12 months is shown as a year in the years, months, and days result. When both dates are included, the extra day is added to these breakdowns too.
Adding months and years
If the resulting month doesn't have that day, the tool uses the last day of the month. For example, January 31, 2026 plus 1 month is February 28, 2026. That's how this tool handles it. Legal and contract deadlines may be counted differently, so check the rules that apply to you.
Limitations
Every calendar day counts, including weekends and holidays. This tool does not calculate business days. Inputs and resulting dates must be in the years 1000 through 9999. The amount to add or subtract must be a whole number from 0 to 999,999.
For birthdays and age in years, use the age calculator.
Frequently asked questions
What if the start and end dates are the same?
The result is 0 days, or 1 day with "Include both dates" checked.
Can I exclude weekends and holidays?
No. This calculator counts every calendar day, so weekends and holidays are included.
What happens when I add a year to February 29?
You get February 28, unless the new year is also a leap year.
Can daylight saving time change the count?
No. The tool counts calendar dates, not hours, so a clock change doesn't affect the result.