Business Days Calculator
Two dates in, the working days between them out: with your holidays taken off.
What is a business day?
A business day is a day the working world is open: Monday to Friday, minus public holidays. Counting them between two dates is not the span divided by seven, because the answer depends on which weekday each end falls on and on which holidays sit in between.
How it works
The calculator walks every day in the range and counts the ones that are working days: Monday to Friday by default, minus any date you list as a holiday.
The last day is counted, because "from the 2nd to the 6th" normally means both ends included. A holiday that falls on a weekend costs nothing, since that day was never going to count.
Dates are read as plain calendar dates rather than moments in time, so no time zone can shift one across midnight and change the answer.
What counts as a working day is an input, not an assumption
The arithmetic here is trivial; the judgement is not. Monday to Friday is the common Western working week, but it is not universal: much of the Middle East works Sunday to Thursday, some contracts are four days, shift patterns ignore the week entirely. And public holidays are national, often regional, and move: Easter alone drags four or five dates around the calendar each year.
A calculator that hard-codes a country is wrong for everyone else and silently wrong for the one it chose as soon as a regional holiday comes up. So the holidays are yours to list, which takes thirty seconds and makes the answer actually true for your office rather than approximately true for someone else’s.
The questions this answers
- How long will this take? a ten-working-day lead time quoted on a Thursday lands a fortnight later, not ten days later. The gap between calendar days and working days is what makes delivery promises slip.
- Is the deadline what I think it is? notice periods, appeal windows, payment terms and statutory deadlines are often written in working days precisely because weekends should not count against them.
- How much capacity is in this period? working days times team size times hours a day is the starting point of every plan. Getting the first number wrong scales the error through everything after it.
- How much leave does this cost? a holiday booked from a Friday to the following Monday is two working days off, not four.
Inclusive or exclusive, and why it matters
The single commonest off-by-one in scheduling is whether the last day counts. "From the 2nd to the 6th" to most people means five days including both ends; "within 5 working days of the 2nd" usually means the clock starts the next day. The two readings differ by one day, which is the difference between delivering on time and delivering late.
This counts the last day by default, which matches the first reading, and lets you turn that off for the second. Whichever you need, the useful habit is to write the end date down explicitly rather than the number of days, because a date cannot be misread and a count can.
What it does not do
It does not know your country’s holidays. That is a choice rather than a gap: a built-in list is wrong the moment you are in a different region, and silently wrong is worse than empty. Paste your own and it is right.
It also does not know about half-days, company shutdowns, individual leave or the fact that nothing gets done between Christmas and New Year. Those are real and they are local; the honest thing is to list them as holidays too, since for a capacity calculation that is exactly what they are.
Questions people ask
How do I count working days between two dates?
Count every day in the range, then drop the weekends and any public holidays that fall on a weekday. From Monday the 2nd to Friday the 13th is twelve calendar days and ten working days.
Is the last day included?
Yes by default, because "from the 2nd to the 6th" normally means both ends. You can turn that off when the clock starts the day after.
Does it know my country’s public holidays?
No, and deliberately: a built-in list is wrong for every other country and for most regions. Paste your own dates and the answer is right for your office.
What if my working week is not Monday to Friday?
Pick the weekdays you actually work. A Sunday-to-Thursday week or a four-day week counts correctly.
What happens to a holiday that falls on a Saturday?
Nothing: it costs no working day, because that day was never going to count. Only holidays that land on a working day reduce the total.