How to Calculate Business Days Between Dates

Delivery windows, notice periods, and payment terms are often quoted in business days rather than calendar days, so knowing how to count business days between dates saves confusion and missed deadlines. Business days are simply the working days of the week, and counting them means excluding weekends and public holidays from your total. This guide explains exactly what counts as a business day, shows how to calculate them by hand, gives a quick estimate for longer spans, and covers the common real-world uses. Because manual counting is fiddly once holidays are involved, our date difference calculator provides the calendar-day total; it does not exclude weekends or public holidays. Use the steps below to subtract those dates under the calendar and boundary rules that apply to you.

What are business days?

A business day, also called a working day, is any day when businesses and banks are normally open. In most countries that means Monday to Friday, excluding Saturday, Sunday, and public holidays. So a deadline of five business days does not mean five calendar days; it skips over any weekends and holidays that fall in between.

Weekends and which days are public holidays vary by country and even region, so always use the calendar that applies to your situation.

How to count them

1. Choose your boundary rule before counting: include both endpoints for an inclusive date range, or exclude the starting date when counting business days after it. Count the calendar dates selected by that rule.
2. Subtract every Saturday and Sunday that falls within it.
3. Subtract any public holidays that land on a weekday.

The result is the number of working days under your chosen calendar and boundary rule. Subtract a holiday only if it falls on a working weekday in the selected range; a holiday on a weekend must not be subtracted twice. Check any observed substitute holiday in the applicable local calendar.

A worked example

Suppose the starting date is Monday, August 10, 2026. Count 10 business days after it, excluding the starting Monday, with a Monday-to-Friday working week and no holidays in the example.

1. Tuesday, August 11 is day 1. Friday, August 14 is day 4.
2. Monday, August 17 is day 5. Friday, August 21 is day 9. Skip both weekends.
3. Monday, August 24 is day 10: 14 elapsed calendar days after August 10.

Excluding the starting Monday, 10 business days later is Monday two weeks later. If instead Monday, August 10 counts as day 1, day 10 is Friday, August 21, which is 11 elapsed calendar days later. If the selected calendar contains a weekday holiday, skip that date and continue counting to the next eligible working day.

Count any range instantly

Our date difference calculator counts the days between any two dates, and our guide on calculating days between two dates covers the calendar-day version in detail.

A quick estimate

For a fast approximation over a longer period, use the fact that five of every seven days are business days.

So 30 calendar days is roughly 30 x 5 / 7, about 21 business days, before subtracting any public holidays. This estimate is close for whole weeks but should be checked exactly when a deadline really matters.

Where business days are used

• Deliveries and shipping: estimated arrival is often given in business days.
• Payment terms: invoices may be due within a set number of business days.
• Notice periods: employment and legal notices are sometimes counted in working days.
• Bank transfers: clearing times are usually quoted in business days.

Frequently asked questions

How do I calculate business days between two dates?

Choose whether to include the starting date and ending date, then count the selected calendar dates. For a Monday-to-Friday schedule, subtract Saturdays, Sundays and applicable weekday holidays, without subtracting any date twice. For example, August 11 through August 24, 2026 includes 14 calendar dates and 10 weekdays before any holiday adjustment.

What counts as a business day?

A business day is a working day when businesses and banks are typically open, usually Monday to Friday. It excludes weekends, normally Saturday and Sunday, and public holidays. The exact weekend days and holiday dates vary by country and region, so use the calendar that applies to your location when counting.

How many business days are in a week?

There are normally five business days in a week, Monday through Friday, with Saturday and Sunday as the weekend in most countries. Some regions observe a different weekend, so the working days can differ. Public holidays that fall on a weekday reduce the number of business days in that particular week.

How do I estimate business days quickly?

Multiply the number of calendar days by 5 and divide by 7, since five of every seven days are working days. For 30 calendar days, that is about 21 business days. This is an approximation that works well for whole weeks; subtract any public holidays and verify exactly when a precise deadline matters.

Do business days include holidays?

Under a calendar that treats public holidays as non-working days, exclude applicable weekday holidays and any observed substitute holidays. Do not subtract a holiday twice when it falls on a weekend. Business, bank and contractual calendars can differ, so use the calendar specified for your deadline.

The bottom line

Use the working week, holiday calendar and endpoint rule that apply to your task. With Monday-to-Friday working days and no holidays, 10 business days after a Monday is Monday two weeks later when the starting date is excluded. Our date difference calculator counts calendar days only; subtract non-working dates separately to get business days.

Further reading

For authoritative background on this topic, see Business day on Wikipedia.