Defaults to today.
How to use the Date Difference Calculator
- 1Choose the start date.
- 2Choose the end date. It defaults to today, so you can see how long ago something happened straight away.
- 3Tick Include the end date if both the first and last day should count, for example for a booking or a leave request.
- 4Tick Count business days only to make weekdays (Monday to Friday) the main result.
- 5Read the total in the highlighted box and the breakdowns underneath.
How the days between dates are counted
By default the calculator counts the days from the start date up to, but not including, the end date. This is the standard way to measure elapsed time: from Monday to the following Monday is 7 days. It matches how you would subtract dates in a spreadsheet.
Some situations count both ends. A hotel booking from the 1st to the 3rd is two nights, but a holiday rental advertised as the 1st to the 3rd inclusive covers three days. Ticking Include the end date adds that extra day. For a fuller explanation with examples, read our guide on how to count the days between dates.
Years, months and days
Months have between 28 and 31 days, so a span in months cannot be found by dividing by 30. The calculator counts whole calendar months forward from the start date, then the remaining days. From January 1 to October 12, 2026 is 9 months and 11 days, which is 284 days in total, or 40 weeks and 4 days.
When the start date falls on a day that a shorter month does not have, such as January 31, the month step lands on that month's last day. So January 31 to March 1, 2026 is 1 month and 1 day. This is the same approach our age calculator uses for birthdays, and it means leap days are always counted correctly: 2024 had 366 days, 2026 has 365.
Business days and working days
With Count business days only, the result shows how many Mondays to Fridays fall in the period. From January 1 to October 12, 2026 there are 202 weekdays and 82 weekend days. Use this to estimate delivery times, notice periods or project schedules that run on working days.
The count excludes weekends but not public holidays, since those differ by country and region. Subtract any holidays that fall within the period yourself. To turn working time into pay, the salary to hourly calculator converts between annual, monthly and hourly figures.
When to use a date difference
Common uses include working out how long you have been in a job or relationship, the length of a contract or lease, the number of days a payment is overdue, or how many days of a trial or warranty have passed. Many legal and financial deadlines are expressed in days, so an exact count avoids costly mistakes.
If you are counting toward a date rather than back from one, the days until calculator shows a live countdown to a holiday, deadline or event.
Learn more
Frequently asked questions
What if the end date is before the start date?
The calculator swaps the two dates and shows a short note, so the difference is always displayed as a positive amount of time.
Does the calculator account for leap years?
Yes. Every date is handled on the real calendar, so February 29 is included in leap years and day counts are exact for any years you choose.
Why are the hours only approximate?
The hour figure multiplies the number of days by 24. In places that observe daylight saving time, the day the clocks change has 23 or 25 hours, so the true number of hours can differ by one for each change in the period.
Should I include the end date?
Include it when every calendar day in the period counts, such as days of leave or event days. Leave it off when measuring elapsed time, such as the age of something or the time between two appointments.
Can I count business days excluding holidays?
The tool removes Saturdays and Sundays only. Subtract the public holidays that fall in your period to get the final number of working days. More tools for dates are on the date and time page.