Business Day Calculator
Counting working days between two dates is the most re-implemented and most often wrong piece of date arithmetic there is, and the reason is always the same: nobody says whether the ends are included. Monday to Friday is five working days by one definition and four by another, and a contract that means one while your spreadsheet means the other is a real argument. This counts both ends, says so plainly, and lets you set which days are working days and which dates are holidays.
What this generator does
Answers two related questions exactly: how many working days lie between two dates, and what date falls a given number of working days from a start date. The countdown planners on this site count backwards from a launch in calendar days; this counts only the days you actually work, and it is explicit that both ends of a range are included — which is the definition most contracts and deadlines use, and the one most spreadsheet formulas do not.
How to use this tool
- Enter the two dates as YYYY-MM-DD.
- Tick which days of the week count as working days.
- Paste any holidays to exclude, one per line.
- Read the count, and the date a given number of working days away.
Understanding the controls
- From and to
- Both dates are included in the count if they are working days. Monday to Friday is therefore five, not four. Giving the dates the other way round gives the same answer.
- Working days
- Defaults to Monday–Friday. Untick a day for a four-day week, or tick only Saturday and Sunday to count weekend cover.
- Holidays
- One date per line as YYYY-MM-DD. A holiday that falls on a non-working day changes nothing, because it was never counted — which is the correct behaviour and a common source of off-by-one errors.
- Add working days
- Counts forward from the start date without counting the start date itself, which is how a notice period is normally read. Negative numbers count backwards.
Worked examples
- Mon 5 to Fri 9 February 2024
- 5 working days — both ends counted.
- Fri 9 to Mon 12 February 2024
- 2 working days, not 4.
- The whole of 2024
- 262 weekdays.
- One working day after a Friday
- The following Monday.
Common use cases
- Working out a contractual deadline stated in working days
- Checking how many working days are left in a quarter
- Adding a notice period or a service-level window to a date
- Planning around a four-day week or a shift pattern that is not Monday to Friday
- Settling a disagreement about whether a deadline has passed
How this generator works
The count walks the range a day at a time and tests each one, which is the slow definition nobody would ship and everybody agrees with — and it is exactly what the tests check the fast path against. Adding working days steps forward or back one day at a time, counting only the days that qualify, so a run of holidays or a long weekend is handled without any special cases.
Randomness and fairness
Nothing here is random. This is a calculator: the same dates and the same holiday list always give the same answer, which is the entire point of using it to settle a deadline.
For how randomness is produced across the whole site, see how Generate Random works.
Assumptions this tool makes
- Both the start and end dates are included in the count where they are working days.
- Adding working days does not count the start date itself.
Limitations and good to know
- It knows no public holidays of its own. Every holiday has to be pasted in, because they differ by country, by nation within a country, and by year.
- It counts whole days. Half-days, part-time patterns and hours are not modelled.
- There is no timezone handling; a date is a date.
- Your holiday list is not saved between visits.
Common mistakes
- Not agreeing whether the ends are included
- This tool includes both. If your contract means something else, subtract one — but decide before the deadline rather than after it.
- Adding a holiday that falls at a weekend and expecting the count to drop
- It was never counted, so removing it changes nothing. That is correct.
- Using the count when you meant to add days
- 'Five working days from Friday' is a date, not a count. Use the add field for that.
Practical tips
- Paste your organisation's holiday list once and read both answers off the same settings.
- For a four-day week, untick the day off rather than adjusting the answer afterwards.
- Where a deadline matters, write down which definition you used alongside the date.
Privacy and your data
The dates and holiday list you type stay in your browser. Nothing is uploaded, nothing is stored between visits, and nothing is written into the page address. Analytics records only that the tool was used.
Frequently asked questions
- Does this include both the start and end dates?
- Yes, where they are working days. Monday to Friday is five working days here. That is the definition most contracts use, and the tool states it rather than leaving you to guess.
- Why are there no public holidays built in?
- Because they differ by country, by nation within a country, and by year, and a wrong holiday list is worse than no holiday list. Paste your own and the answer is exactly right for you.
- Can I use it for a four-day week?
- Yes — untick the day you do not work. Everything else, including adding working days, follows from that.
Related generators
- Date Range SplitterDivides a date range into equal contiguous chunks that cover it exactly — no gaps, no overlaps, no lost days.
- Nth Weekday Date CalculatorFinds dates defined by a rule rather than a number — the fourth Thursday, the last Monday — and says plainly when a fifth one does not exist.
- Recurring Date GeneratorExpands a repeat rule into actual dates — and says what happened when a month has no 31st or no fifth Tuesday.
- Launch Countdown PlannerTurns a launch date into working-day start dates for every task, and flags what will not fit.