How the days are counted
The calculator turns each date into a day number and subtracts. That is the same as counting how many times you turn a page on a calendar to get from the first date to the second.
By default the result counts the gap between the dates, so Monday to Friday of the same week is 4 days. If both the first and the last day should count, as with annual leave or a course that runs Monday to Friday, tick Include the end date and the answer becomes 5.
The same period is also shown in weeks, in years, months and days, and in business days. Leap years are handled automatically: February 2024 had 29 days, February 2026 has 28.
Worked example: days until a deadline
Say today is 21 October 2026 and a project is due on 25 December 2026.
- Calendar days: 10 days left in October, 30 in November and 24 in December before the 25th, so 65 days.
- In weeks: 65 ÷ 7 = 9 weeks and 2 days.
- In months: 21 October to 21 December is 2 months, then 4 more days, so 2 months and 4 days.
- Business days, Monday to Friday: the 65 days contain 18 weekend days, leaving 47 business days.
If 26 November is a public holiday where you work, add it under Working days and the count drops to 46. A holiday that falls on a Saturday or Sunday is ignored, because that day was not a working day anyway.
Business days and different weekends
Not everyone works Monday to Friday. Open Working days and click the days that are your weekend:
- Saturday and Sunday: the default, and the most common weekend worldwide.
- Friday and Saturday: used in several Gulf and Middle Eastern countries.
- Sunday only: common for shops and some offices that work six days a week.
Paste your holidays one per line, for example 2026-12-25 or 25 Dec 2026. Dates written only in numbers like 12/05/2026 are not accepted, because they mean 12 May in some countries and 5 December in others.
Adding and subtracting dates
In Add or subtract mode you can move a date forward or back by any mix of years, months, weeks and days. Years and months are applied first, then weeks and days. When the result would land on a day that does not exist, such as 31 February, the date moves to the last day of that month.
| Start date | Change | Result |
|---|---|---|
| 31 Jan 2026 | + 1 month | 28 Feb 2026 |
| 31 Jan 2024 | + 1 month | 29 Feb 2024 (leap year) |
| 29 Feb 2024 | + 1 year | 28 Feb 2025 |
| 21 Oct 2026 | + 90 days | 19 Jan 2027 |
| 21 Oct 2026 | + 10 business days | 4 Nov 2026 |
| 21 Oct 2026 | − 6 months | 21 Apr 2026 |
Tick Count days as business days to skip weekends and holidays, which is how “10 working days” in a contract or a refund policy is usually meant. Weeks, months and years are always calendar units.
Everyday uses
- Notice periods and contracts. Find the last day of a 30-day or 3-month notice period.
- Payment terms. An invoice dated 21 October with “net 30” terms is due 30 days later, on 20 November.
- Travel and visas. Count the days of a trip. Many stay rules count both the arrival and departure days, so include the end date.
- Countdowns. See how many days or weeks are left until a wedding, an exam or a holiday. For a live countdown in minutes and seconds, use the online timer.
Tips
- Check whether your rule counts calendar days or business days. “Within 14 days” and “within 10 working days” can be very different dates.
- Results do not depend on your time zone or daylight saving time, because only whole dates are used.
- To find someone’s exact age, or your age on an exam cut-off date, use the age calculator. To add up hours and minutes, or find the time between two clock times, use the time calculator.