FREE CALCULATOR · TIME & DATE

Business Days Calculator

Deadlines, invoices, and shipping promises run on business days — not calendar days. Count the workdays between two dates with your own weekends and holidays, or add N business days to any date and land on the right one.

Count the days that actually count

Pick a mode: count the business days between two dates, or add N business days to a start date. Weekends and holidays are yours to define — the calendar strip paints every day so you can see the math.

How it works: the calculator walks every date from start to end — both endpoints counted — and marks each one a workday, a weekend day, or a holiday. A holiday that lands on a weekend counts as a weekend day, not both. In "Add business days" mode the start day is day zero: day 1 is the next business day. All date math runs in UTC so daylight-saving changes can never shift the answer. Estimates only, not legal advice — contract deadlines follow the contract's own counting rules.

How business days are calculated

"Respond within 10 business days" sounds precise until you try to circle the date. The naive answer — count 10 days forward — lands you on the wrong day, because weekends and holidays hide inside every range. The reliable method is a three-step subtraction that works for any workweek and any holiday list.

The reason it is a subtraction and not a count is that calendars are uneven: a 10-business-day promise starting on a Monday crosses two weekends, but the same promise starting on a Wednesday crosses only one before it ends — or two, depending on where it lands. Walking the range day by day never misses, which is exactly what the calculator does and what the calendar strip below the result shows you.

The formulas

business days = calendar days − weekend days − holidays on would-be workdays · add N business days: walk forward from the start date, counting only workdays, until N are counted

The shortcut for long ranges: count the full weeks, multiply by your workdays per week (usually 5), then walk the leftover days one by one. A standard full-time year holds about 260 weekdays — the same figure behind hourly-to-salary math.

Worked example: Monday, October 5 → Friday, October 16, 2026

Start Monday, October 5, 2026, end Friday, October 16, 2026, Saturday–Sunday weekend, no holidays.

1. Calendar days: October 5 through October 16, both counted = 12 days.

2. Weekend days: October 10–11 (Saturday–Sunday) = 2 days.

3. Holidays: none entered = 0 days.

4. The answer: 12 − 2 − 0 = 10 business days.

5. The reverse check: add 10 business days to Monday, October 5 — day 1 is Tuesday the 6th, and day 10 lands on Monday, October 19, 2026. The round trip confirms the counting.

Where this comes in handy

Project deadlines and SLAs: "respond within 10 business days" means a concrete date — use add mode to circle it, then check the calendar strip. Date arithmetic on loans works the same way — see the loan payoff date calculator.
Invoice and payment terms: "net 10 business days" is about two calendar weeks; price the delay into cash-flow plans with the savings goal calculator.
Shipping and delivery estimates: a "5 business day" delivery starting Friday lands the next Friday, not Wednesday — count it before you promise it.
Legal and court deadlines: filings, notice periods, and cure periods all run on business days; confirm the governing rules, since some exclude the start day.
Workweek math: overtime rules and annual pay both rest on the 5-day week — price extra hours with the overtime pay calculator or convert a wage with the hourly to salary calculator.
Learning the method: the free business-days guide walks through the 3-step method, holiday traps, custom workweeks, and the 10-business-day rule of thumb.

Business days calculator — frequently asked questions

Are the start and end dates both counted?

Yes — on this calculator, both endpoints count if they are workdays, so Monday to Friday is 5 business days. That is the most common convention, but some contracts and statutes count exclusively (start day not counted). If your document says "within 10 business days after October 5," the answer is usually October 19, not October 16 — read the exact wording, and when in doubt ask the other party which convention they use.

What happens when a holiday falls on a weekend?

It counts as a weekend day only — never twice. In the United States, a federal holiday landing on a weekend is usually observed on the nearest weekday (Friday or Monday), and it is the observed day that offices close. Enter the observed date in the holiday list, not the calendar date of the holiday.

Which holidays should I enter?

The ones that actually stop the work you are measuring: federal holidays for government deadlines, your company's list for HR timelines, the other country's list for international shipments. The calculator deliberately ships with no built-in holiday list — a wrong guess about your holidays is worse than asking you to type them.

Can I use a Friday–Saturday or Sunday-only weekend?

Yes — the weekend presets cover Saturday–Sunday, Friday–Saturday, and Thursday–Friday (common in the Middle East), plus single-day weekends and no weekend at all for round-the-clock operations. The strip and the tile counts all follow whichever pattern you pick.

In "add business days" mode, is the start day counted?

No — the start day is day zero, and day 1 is the next business day. So 10 business days from Monday, October 5, 2026 lands on Monday, October 19, 2026. This matches how delivery estimates and notice periods are normally quoted.

What is the difference between business days and working days?

In everyday speech they overlap, but "business day" has the sharper meaning: a weekday that is not a holiday. "Working day" is sometimes used for any day you happen to work — including a Saturday shift. For anything with consequences (contracts, filings, payments), write "business day" and define the holidays.

Why do 10 business days equal about 14 calendar days?

Because almost every 10-business-day stretch crosses two weekends. The rule of thumb: multiply business days by 7/5 to get calendar days. Ten business days ≈ 14 calendar days, five ≈ 7 — close enough for planning, but count exactly when the date matters.

Learn the method: the free business-days guide walks through the 3-step counting method, the long-range shortcut, holiday traps, custom workweeks, and the 10-business-day rule of thumb — step by step.