About the Days Between Dates
Count the days between two dates, and see the same gap as weeks and days, as years, months and days, and as weekdays (Monday to Friday). It is useful for deadlines, notice periods, trips, countdowns and working out how long ago something happened.
You choose whether the last day counts. By default it doesn't, the way ages and hotel nights are counted; tick the box to count both the first and last day, as you would for an event or a leave request.
How it works
Each date is turned into a day number on one continuous count, and the difference between the two numbers is the number of days. Because it works with whole calendar days and never with clock times, a daylight-saving change between the dates can't add or lose an hour and nudge the answer.
Leap years follow the Gregorian rule: a year divisible by 4 is a leap year, except century years, which are leap years only when divisible by 400. So 2000 had a 29 February and 1900 didn't.
For the years-months-days figure, whole months are counted forward from the start date. If the start is the 31st and a month is shorter, that month's last day is used, then the remaining days are added.
days = day number(end) − day number(start) (+1 if the end date is included) weeks = days ÷ 7, remainder = days left over weekdays = 5 × full weeks + Monday–Friday days in the part-week
Assumptions and limits
- Dates use the Gregorian calendar for every year from 1 to 9999 (the 'proleptic' Gregorian calendar used by ISO 8601), including years before countries adopted it.
- Weekdays are Monday to Friday. Public holidays differ by country and region and are not removed.
- If the end date is before the start date, the two are swapped and the page says so; the count is never negative.
Worked examples
New Year's Day to Christmas Day 2026
1 January 2026 is a Thursday and 25 December 2026 a Friday. The gap is 358 days: 51 weeks and 1 day, or 11 months and 24 days. 256 of those days fall on a weekday.
How long until 25 December, from 13 October 2026
18 days remain in October after the 13th, then 30 in November and 25 in December: 18 + 30 + 25 = 73 days.
Working days in October 2026, inclusive
October 2026 starts on a Thursday and has 31 days: four full weeks give 20 weekdays, and the last three days (Thursday 29, Friday 30, Saturday 31) add two more, so 22 weekdays.
Leap years at a glance
| Year | Leap year? | Days in the year | Why |
|---|---|---|---|
| 1900 | No | 365 | Century year not divisible by 400 |
| 2000 | Yes | 366 | Divisible by 400 |
| 2024 | Yes | 366 | Divisible by 4 |
| 2026 | No | 365 | Not divisible by 4 |
| 2028 | Yes | 366 | Divisible by 4 |
| 2100 | No | 365 | Century year not divisible by 400 |
How to use the Days Between Dates
- Pick the start date. Use the date picker, or the Start today button.
- Pick the end date. Choose whether to include the end date in the count.
- Read the result. Days, weeks, months and weekdays appear at once, with the working underneath.
Frequently asked questions
Does the count include the start and end dates?
By default it counts the start date but not the end date, so Monday to the following Monday is 7 days. Tick 'Include the end date' to count both, which makes the same span 8 days; use that for events and leave requests.
How are leap years handled?
With the Gregorian rule used worldwide: every fourth year is a leap year, but century years count only if divisible by 400. That is why 2000 had 366 days while 1900 and 2100 have 365.
Why is the months figure sometimes surprising around month ends?
Months have different lengths, so 'one month after 31 January' has no exact answer. The calculator uses the last day of the shorter month (29 February in 2024), then counts the remaining days, and the working line shows exactly which dates were used.
Are public holidays taken out of the weekday count?
No. Holidays vary by country, region and employer, and some change every year, so the weekday figure only removes Saturdays and Sundays. Subtract your own holidays from it if you need working days.
Can I count backwards, or use dates long ago?
Yes. If the end is earlier than the start the dates are swapped, and any date from year 1 to 9999 works. Very old dates use today's calendar rules, which may not match the calendar people used at the time.
Sources
- ISO 8601-1:2019, Date and time — the Gregorian calendar and leap-year rule
- Meeus, Astronomical Algorithms (2nd ed.), ch. 7: Julian Day Numbers, used to check the counts
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