Days Between Dates
Two dates. The end date is not counted.
The question hidden in "how many days"
There are two reasonable answers, and they differ by one.
- The difference between Monday and Friday is 4 days. That is what this page gives, and it is what you want for a deadline, an age, or a gap between events.
- Counting inclusively gives 5 days, because you count Monday itself. That is what you want for a hotel stay, a holiday allowance, or a notice period.
Neither is wrong; they answer different questions. If your figure is out by exactly one, this is why.
Months and years are approximations here
The day count is exact. The month and year figures divide by averages — 30.4375 days and 365.2425 days — because months genuinely vary in length.
The calendar breakdown in the working below is the honest version: it counts real months. Between 31 January and 28 February is one month by the calendar and 28 days by the clock, and both statements are true.
Why this works in UTC
Doing date arithmetic in local time means daylight saving can add or remove an hour in the middle of your range. If the calculation rounds, that hour can flip the answer by a whole day. Working in UTC removes the problem entirely, which is why every date here is treated as a whole day rather than a moment.
The 365.2425 figure
A year is not 365 days, or 365.25. The Gregorian calendar adds a leap day every four years, skips it on century years, and puts it back on years divisible by 400. That averages to 365.2425 days — which is why 1900 was not a leap year and 2000 was.
Common uses
- Days until a deadline or since an event.
- Length of a contract or a notice period.
- Working out an interest period in days.
- Project planning, where working days matter more than calendar days.
The working, step by step
Questions people ask
Is the end date included?
No. Monday to Friday counts as 4 days. If you need it included — for a hotel stay or a notice period — add one.
Why are the month and year figures approximate?
Because months vary in length. Those figures divide by averages; the calendar breakdown in the working counts real months.
How many days are in a year exactly?
365.2425 on average. The Gregorian calendar adds a leap day every four years, skips century years, and restores it every 400 — so 1900 was not a leap year and 2000 was.
Does daylight saving affect the answer?
Not here. Every date is treated as a whole day in UTC, so a clock change cannot shift the count.
Worked out in the page
The arithmetic runs in your browser. No date you type is sent anywhere, which matters for the ones that are nobody else's business — a birth date, a due date, a notice period. There is no server here to receive them. The about page lists every request the site makes.