How to Count Business Days Between Two Dates

What is a business day?

A business day is any day that is not a Saturday, Sunday, or public holiday. In most Western countries this means Monday through Friday, minus nationally recognised holidays. The precise definition can vary by industry and jurisdiction: some financial contracts treat only banking days as business days, while construction contracts may use calendar days for certain clauses and business days for others.

When a law, contract, or invoice specifies a time limit in business days, the intention is to exclude non-working days so that deadlines are always reachable during normal office hours.

The standard counting method

The most common convention is to exclude the start date (day zero) and count every subsequent weekday that is not a public holiday up to and including the end date. This is the method used by Excel's WORKDAY and NETWORKDAYS functions, as well as most legal and financial frameworks.

• Start date = day 0 (not counted).
• Each weekday after the start date = +1 business day.
• Saturdays, Sundays and public holidays = not counted.
• End date = counted if it is a weekday and not a holiday.

Example: from Monday 5 May to Friday 9 May is exactly 4 business days (Tuesday, Wednesday, Thursday, Friday — Monday the 5th is day zero).

Including the start date

Some contexts count the start date as day one. This is common in HR notice periods and some project schedules. If your contract or handbook says the notice period starts on the day the letter is received, you would include that day. In this case, Monday 5 May to Friday 9 May would be 5 business days. Always check your contract or the applicable law to know which convention applies.

Handling public holidays

Any public holiday that falls on a weekday reduces the business day count by one. If a holiday falls on a Saturday or Sunday, many countries observe it on the nearest weekday (the "observed" date). For example, if Christmas Day falls on a Saturday, the US observes it on the preceding Friday, making that Friday a non-business day.

• Always use the country-specific holiday calendar that applies to your context.
• For multinational contracts, specify which country's holidays apply, or list holidays explicitly.
• For construction and public works contracts in France, jours fériés are typically excluded from délais en jours ouvrés.

Manual counting vs. a calculator

For short periods, manual counting on a calendar is feasible. For anything beyond a week, or when precision matters, a calculator eliminates errors. Manual counting fails when you forget a public holiday, miscalculate across month boundaries, or accidentally count a Saturday. An automated tool applies the holiday calendar consistently and handles year boundaries correctly.

• Manual counting is prone to off-by-one errors at the start and end of the range.
• Holiday rules (observed dates, moveable feasts like Easter) are complex to apply by hand.
• A calculator also lets you export the day-by-day breakdown to verify the result.

Common use cases

Business day counting is required across many professional situations:

• Payment terms: Net-30 means payment is due 30 business days after the invoice date.
• Notice periods: Employment contracts typically specify notice in working weeks or days.
• Legal deadlines: Court filing deadlines and administrative response times are usually expressed in business days.
• Delivery windows: "Ships in 5 business days" means five working days, not five calendar days.
• Project planning: Sprint durations and milestone dates are planned in working days.

Frequently asked questions