Business Days vs Calendar Days: What's the Difference?

Calendar days count every single day of the week — Monday through Sunday, including weekends and public holidays. When you count 7 calendar days from Monday, you land on the following Monday.

Business days (also called working days) count only Monday through Friday, excluding public holidays. If a business is closed on a bank holiday, that day does not count.

• Calendar day: Any day of the week (Mon–Sun), including weekends and holidays.
• Business day: Monday–Friday, excluding public holidays.

Suppose a contract states delivery within 5 business days from Monday, April 7. Counting only weekdays, that means delivery by Friday, April 11 — Saturday and Sunday are skipped entirely.

The distinction between business and calendar days is critical in several real-world contexts:

• Contracts and legal deadlines: Courts and contracts typically use business days for response deadlines, appeal windows, and notice periods.
• Shipping and delivery: Courier services often quote business-day delivery times. A "3-business-day" shipment ordered on Friday may not arrive until Wednesday.
• Payroll: Some payroll cycles count bi-weekly business days, affecting when deposits clear.
• Banking: Fund transfers and cheque clearances are measured in business days, not calendar days.

Public holidays vary significantly by country, state, and even industry. In the United States, federal holidays are not always observed by every employer. In the United Kingdom, bank holidays differ between England, Scotland, and Northern Ireland.

When counting business days for a deadline, always check whether any public holidays fall within the window — each one adds an extra calendar day to the overall count. Some contracts explicitly define which holiday schedule applies.