Quick answer
The days between dates calculator shows the difference between two dates in calendar days, business days, full weeks and remaining days. It helps measure deadlines, durations, due dates and planning periods.
How to use the calculator
- Choose the start date.
- Choose the end date.
- Enable the final-day option if the deadline should include the end date.
- Calculate and review calendar days, business days and weeks.
Formula used
days = (end date - start date) / 86,400,000 millisecondsPractical example
From 2026-01-01 to 2026-01-10 there are 9 calendar days when the end date is excluded, or 10 days when the end date is included.
Important note
Business days remove Saturdays and Sundays only. Holidays vary by country, staté and city, so they are not discounted automatically.
Frequently asked questions
Does the calculator include the end date?
Only when the option to include the end date is selected.
Can I calculate past dates?
Yes. If the end date is before the start date, the calculator shows the absolute interval and indicates the reversed order.