Quick answer. Pick a start and end date to see the gap in years, months and days, total days, weeks and business days. Tick Include the end date to count both days (1 to 31 January = 31 days). Need to know the date 90 days from today? Switch to Add or subtract.
How to use the date difference calculator
- Days between dates: choose a start date and an end date. The result updates instantly. If the end is before the start, the dates are swapped and you are told.
- Include the end date when you want to count both the first and the last day, for example the length of a holiday, a hotel stay or a notice period “from 1 to 31 March inclusive”.
- Business days skips weekends. Pick Saturday and Sunday, Friday and Saturday (common in parts of the Middle East) or another option.
- Add or subtract: pick a date and add or take away days, weeks, months or years, for example a 90-day deadline, a 6-month warranty or a due date.
- Counting down? When the end date is in the future, use the countdown timer link for a live days-until clock you can share.
How the years, months and days are counted
The calculator counts whole calendar months from your start date, then the days left over. It never assumes a month has 30 days or a year has 365. From 15 January to 14 February is 30 days, not one month, because the 15th has not come round again. From 15 January to 15 February is exactly 1 month, even though that is 31 days, while 15 February to 15 March is also 1 month but only 28 days in 2026.
| From | To | Result | Why |
|---|---|---|---|
| 31 Jan 2026 | 28 Feb 2026 | 1 month | February has no 31st, so its last day completes the month |
| 31 Jan 2026 | 1 Mar 2026 | 1 month, 1 day | One month reaches 28 Feb, plus 1 day |
| 29 Feb 2024 | 28 Feb 2025 | 1 year | Leap-day dates count a year on 28 February in common years |
| 1 Jan 2024 | 1 Jan 2025 | 1 year = 366 days | 2024 is a leap year |
| 1 Jan 2026 | 31 Dec 2026, end included | 1 year = 365 days | Both ends counted |
The same rules are used by our age calculator, so an age and a date gap always agree. When adding months, a day that does not exist in the target month moves to the last day of that month: 31 January + 1 month = 28 February (29 in a leap year), and 29 February 2024 + 1 year = 28 February 2025.
Leap years
A year is a leap year if it divides by 4, except century years, which must divide by 400. So 2024 and 2000 are leap years, but 1900 and 2100 are not. Totals across February always use the real number of days, 28 or 29.
Business days and other totals
Business days count Monday to Friday by default, from the start date up to the end date (counting the end date only when you tick the box). Public holidays differ by country and are not removed, so subtract your own. Weeks are total days ÷ 7 with the leftover days shown. Hours and minutes are whole days × 24 and × 1,440. This is a calendar count, so a daylight-saving change is not treated as a 23- or 25-hour day.
Frequently asked questions
How do I calculate the number of days between two dates?
Enter a start date and an end date. The calculator subtracts them using real calendar dates and shows total days, plus years, months and days, weeks and business days.
Should I include the end date?
Include it when both the first and last day count, such as a stay from the 1st to the 5th that is 5 days long. Leave it off for elapsed time, where the 1st to the 5th is 4 days.
How are leap years handled?
Every calculation uses the real calendar, so February has 29 days in leap years (2024, 2028) and 28 otherwise, and century years follow the divide-by-400 rule.
What is 31 January plus one month?
28 February, or 29 February in a leap year. When the target month is shorter, the date moves to that month’s last day.
Does it count business days?
Yes. It counts weekdays and skips the weekend you choose (Saturday–Sunday by default, or Friday–Saturday and other options). Public holidays are not removed.
How do I find the date 90 days from today?
Switch to Add or subtract, press Today, choose + Add, enter 90 and pick Days.
Can I see a live countdown to the date?
Yes. When the end date is in the future, press Live countdown to this date to open it in our countdown timer, which you can share.