Business days between dates:
count only the days people actually work

What counts as a business day?

A business day is a day on which offices, banks or couriers normally work. By default that means Monday to Friday, minus public holidays that fall on those days. Saturdays and Sundays are excluded.

In practice the definition depends on who is counting. Many Indian workplaces run a six-day week, others take a Saturday off alternately, and a bank's holiday list is not the same as a courier's. Settle the pattern first, because it changes the answer more than any other choice.

The idea is the same for a short task and a long project. You are removing the days nobody is available, so that the number left reflects real working time.

You will meet the term in delivery promises, payment terms, notice periods and regulatory deadlines, where a 10-business-day window is a very different length from 10 calendar days.

Business days formula and the fast method

Decide the end-date rule before you start. Subtracting 1 October from 30 October gives 29 calendar days, while counting both end dates gives 30. That one-day choice carries through to the business day total.

To count quickly without a calendar, use whole weeks. Every full week contains five business days, so only the leftover days need a look.

1. 1Count the calendar days in the period, and decide whether both end dates count.
2. 2Divide by 7. Multiply the whole weeks by 5.
3. 3Check which weekdays the leftover days fall on and add the weekdays only.
4. 4Subtract any holidays that fall on a Monday to Friday.

Example: 1 to 30 October 2026

The fast method gives the same answer. From Thursday 1 October to Wednesday 28 October is exactly four whole weeks, which is 4 × 5 = 20 business days. The two leftover days, Thursday 29 and Friday 30, are both weekdays, so 22. Subtract the holiday and you reach 21.

The count includes both 1 and 30 October, so the first day is counted. If a contract says the days run 'from' 1 October, day one is 2 October and the count drops accordingly.

Holiday dates change from year to year and between states, so take the list from the official notification for your location and organisation.

How the work week changes the answer

The same 30 calendar days give three different answers depending on the pattern. All three below assume the single holiday on 2 October.

Half-days complicate things further. Simple counts treat a half-working day as a full business day, but a contract or internal policy may count it differently, so check before you rely on a figure.

A four-day swing from one date range is easily enough to miss a deadline. When a deadline matters, confirm the work-week pattern in the document that sets it.

Adding business days to a date

The reverse question is common too: what date is 10 business days from now? Start on the day after the start date, skip weekends and holidays, and count until you reach 10.

Ten business days turned into 15 calendar days because of two weekends and a holiday. For promises of 'delivery in 10 business days', that gap is worth explaining to the customer.

Going backwards works the same way. To find the date 10 business days before a deadline, move back one day at a time and skip the same weekends and holidays, which tells you the latest date work can start.

To count calendar days with no exclusions, the days between dates guide on this site covers the plain count.

Where the business day count is used

Payment terms are the most common use. An invoice dated Thursday, 1 October 2026 with terms of 15 business days falls due on Friday, 23 October when 2 October is a holiday. In calendar terms that is 22 days, not 15.

Notice periods and service-level promises are the second. A support team promising a reply in two business days has until Tuesday if the ticket arrives on a Friday, because the weekend does not count.

For planning, it helps to know how many weekdays a month holds before any holidays. In 2026 the monthly weekday counts run from 20 in February to 23 in July and December, and the full year has 261 weekdays.

Holidays then reduce each figure, and some of the national and religious holidays move from year to year, so rebuild the list annually rather than copying last year's.

Mistakes that throw the count off

• Counting both end dates when the document says 'from'. The two conventions differ by one day, which is the margin that decides many deadlines.
• Subtracting a holiday that falls on a weekend. It is already excluded, so deducting it again undercounts.
• Using a national list for a local deadline. States, banks, courts and companies each publish their own holiday lists.
• Forgetting cut-off times. A payment made after the bank's closing time is often treated as received on the next business day.
• Treating optional or restricted holidays as closures. Some organisations give a choice of holidays, so your own working calendar may differ from the published list.
• Assuming everyone works the same week. A supplier on a six-day week and a customer on a five-day week will count a different number of days.

The workdays estimate calculator on this page gives a quick figure for a period. Always check it against the holiday list that actually applies to you.