How to Calculate Working Days

The basic approach

Business days are the weekdays between two dates, inclusive of both endpoints. The simplest method counts every day in the range and subtracts the weekends.

• Total calendar days = difference between the dates + 1
• Weekend days ≈ (total days ÷ 7) × 2, adjusted for where the range starts
• Business days = calendar days − weekend days − public holidays

A worked example

Take 1 January 2026 (a Thursday) to 31 January 2026 (a Saturday): 31 calendar days, of which 8 are weekend days (4 Saturdays and 4 Sundays).

That leaves 23 weekdays. If two public holidays fall on weekdays inside the range, the result is 21 business days.

Watch out for these traps

• Inclusive counting: most business-day counts include both the start and end date. Check which convention your contract uses.
• Public holidays that fall on a weekend do not reduce the weekday count — unless your country observes them on the following Monday.
• Different weekends: Friday–Saturday weekends are standard in much of the Middle East, and Sunday-only weekends exist in some industries.
• Half days: some countries treat certain days (such as Christmas Eve) as half working days.
• Time zones: count using calendar dates, not timestamps, to avoid daylight-saving shifts.

For legal deadlines, always check whether the rule says "working days", "business days", "clear days" or "calendar days" — the difference can be a week.

What business days are used for