Business Days Calculator

What the business days calculator does

Plenty of deadlines are not measured in calendar days but in working days, the Monday-to-Friday kind, and that is exactly what this tool works in. It does two jobs. It counts how many working days fall between two dates, and it takes a start date and adds a number of working days to find the date you land on. Either way, it skips every Saturday and Sunday, so the answer reflects a normal working week rather than the raw calendar.

That makes it the right tool for project timelines, delivery estimates, and any commitment quoted as a number of business days.

How to use it

1. Calculator mode. Choose Count business days to count the working days between two dates, or Add business days to add working days to a start date.
2. For counting. Enter the start and end dates, and choose whether to include the last day.
3. For adding. Enter the start date and how many business days to add.

Press Calculate for the result, or Reset to clear the form.

The two modes, and when to use each

The counting mode answers "how much working time is in this window." You have two dates, and you want to know how many actual working days sit between them, which is the question behind staffing a project or sizing a piece of work. The adding mode answers the opposite, "what date is this many working days away." This is the one a lot of plain date tools leave out, and it is the one you want for a commitment like "we will respond within 10 business days" or "delivery in 5 working days," where you need the actual date that promise lands on.

How it counts

It works the calendar one day at a time. In counting mode it steps from the start date to the end date and tallies up only the days that fall Monday to Friday, ignoring the weekends. In adding mode it steps forward from your start date, counting each weekday it passes and skipping the weekends, and stops when it has counted the number of business days you asked for, which is the date it gives you. The include-last-day choice in counting mode decides whether the end date itself is counted as one of the working days.

An example with real numbers

Take a Monday, say 6 January 2025, and add 10 business days.

• The start Monday itself is not counted, so the days after it, Tuesday to Friday, give four business days.
• The weekend is skipped, and the next full working week adds five more, taking the count to nine.
• The following Monday is the 10th business day, so you land on Monday 20 January, which is 14 calendar days after the start even though only 10 were working days.

That gap between 10 working days and 14 calendar days is the whole point of the tool. The two weekends in the middle do not count toward the ten, but they still pass on the calendar.

The one thing it does not know: holidays

Here is the honest limit, and it is worth knowing before you rely on a date. The tool removes weekends, but it does not remove public holidays, and that is on purpose, because holidays are different in every country and often in every region within one. There is no single list it could use that would be right for everyone. So if your span runs across a public holiday or two, the working-day count will be a touch high, and you should subtract those days yourself. For most planning that is an easy adjustment, and it keeps the tool honest rather than guessing at a holiday calendar that might not be yours.

Questions people ask

What counts as a business day?

Any day from Monday to Friday. The tool treats Saturdays and Sundays as non-working and leaves them out of every count.

Does it account for public holidays?

No, only weekends. Because holidays vary so much from one place to another, the tool leaves them out, so subtract any that fall inside your range yourself.

Can it tell me the date a number of working days from now?

Yes, that is the adding mode. Enter a start date and a number of business days, and it gives you the date you reach once the weekends along the way are skipped.

How do I work out a "within 10 business days" deadline?

Use the adding mode. Put the start date in, add 10 business days, and the result is the date the commitment is due, with the weekends already taken out.