Business Days Calculator
Need to know how many working days fall between two dates? This calculator counts every Monday through Friday between your start and end dates, excluding Saturdays and Sundays. It is useful for calculating contract deadlines, project timelines, payroll periods, loan funding windows, and legal notice periods. Note that federal holidays are not automatically subtracted; consult the OPM federal holiday schedule at opm.gov if your context requires excluding them.
Business days formula
Business days = count of Mon-Fri days in [start, end)
Calendar days = end date - start date (in days)
The calculator iterates each day from start to end (exclusive), checks if it is a weekday (getDay() returns 1-5 for Monday-Friday), and increments the count. This is exact for any date range.
Common business day rules
- USPS First Class Mail: 1 to 5 business days delivery time (opm.gov).
- ACH bank transfers typically settle in 1 to 3 business days.
- Many legal filings have deadlines expressed in business days from service or notice.
- Employment contracts often specify notice periods in business days.
- Federal holidays (11 per year): New Year's Day, MLK Day, Presidents Day, Memorial Day, Juneteenth, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving, Christmas.
Business days: frequently asked questions
How are business days counted?
Business days are weekdays: Monday through Friday. Saturdays and Sundays are excluded. This calculator counts every calendar day between the start and end dates and subtracts the weekends. Federal holidays are not automatically excluded because holiday schedules vary by employer and country.
Are federal holidays included as business days?
This calculator counts all weekdays without subtracting federal holidays, because holiday observance varies by employer, state, and industry. The U.S. Office of Personnel Management lists the 11 federal public holidays at opm.gov if you need to manually subtract them.
Is the start date or end date included in the count?
The calculator includes the start date if it is a weekday and counts up to (but not including) the end date, which is the most common business convention. Check with the specific legal or contractual context for your situation, as some contexts count differently.
What is the difference between business days and calendar days?
Calendar days count every day including weekends and holidays. Business days count only Monday through Friday. A 10-business-day period can span 12 to 16 calendar days depending on where weekends fall.
Why do contracts specify business days instead of calendar days?
Contracts use business days because many tasks (mail delivery, banking, legal filings) can only be completed on weekdays. Using business days avoids the unfairness of deadlines falling on weekends when action is not possible.
Official sources
- U.S. Office of Personnel Management, federal holidays: opm.gov federal holidays.
- U.S. Naval Observatory, calendar resources: aa.usno.navy.mil.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.