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How to Count Working Days Between Two Dates

By Reeliy Editorial Team · · 3 min read

Delivery estimates, notice periods, payment terms and project plans are often written in working days (also called business days) rather than calendar days. A working day is, in most places, a weekday that is not a public holiday. The result is always shorter than the calendar count, and the gap is bigger than most people expect.

You can count working days quickly with one shortcut, as long as you decide up front which days are excluded and whether the start date counts. This guide walks through both, with a worked example you can check.

The weeks-times-five shortcut

A full week of seven days always contains five weekdays, whichever day you start on. So split the span into whole weeks plus a few leftover days, and count the weekdays in the leftovers one by one.

working days = full weeks × 5 + weekdays in the leftover days − weekday holidays

Worked example: Friday 9 October 2026 to Wednesday 4 November 2026, counting both ends. That is 27 calendar days.

  1. 27 days is 3 full weeks (21 days) plus 6 leftover days.
  2. The 3 full weeks run Friday 9 October to Thursday 29 October and hold 3 × 5 = 15 working days.
  3. The 6 leftover days are Friday 30 October to Wednesday 4 November: Friday, Saturday, Sunday, Monday, Tuesday, Wednesday. The weekdays among them are Friday, Monday, Tuesday and Wednesday, so 4.
  4. The total is 15 + 4 = 19 working days, before any holidays.

If a holiday falls on a Monday inside that span, the answer drops to 18. A holiday that falls on a Saturday or Sunday changes nothing, because those days were already excluded.

Does the start day count?

The count of 19 above includes both Friday 9 October and Wednesday 4 November. If the start day is excluded, as it often is when you count from an order date or a notice date, the same span is 18 working days.

  • Counting "within 5 working days" of an order usually starts with the next working day, but check the wording of the policy or contract.
  • A project plan that includes the first and last day uses the inclusive count.
  • Say which convention you used when you give the number to someone else.

Adding working days to a date

Going the other way, ask what the date is after N working days. Because 5 working days is exactly one calendar week, every multiple of 5 is simple: 10 working days after a Thursday is the Thursday two weeks later.

Worked example: 10 working days after Thursday 22 October 2026, with no holidays. Two weeks later is Thursday 5 November 2026. If Monday 26 October is a public holiday, there are only 9 working days by 5 November, so the answer moves to Friday 6 November.

For a number that is not a multiple of 5, remove whole weeks first and walk the remainder. For 7 working days after a Wednesday, add 5 (the next Wednesday), then 2 more working days: Thursday and Friday. The answer is that Friday.

Holidays and different weekends

Only holidays that fall on a weekday matter. Check three details before you subtract them:

  • Some holidays are observed on a different day when the actual date falls on a weekend, such as the nearest Monday or Friday.
  • Public holidays vary by country, and sometimes by region or by employer. A calendar from one place may not fit another.
  • In some countries the weekend is not Saturday and Sunday, so the weeks-times-five shortcut still holds but the leftover days must be counted against the right weekend.

Half days, bridge days and company closures are not usually treated as holidays unless your agreement says so.

Common mistakes

  • Multiplying the calendar days by 5/7 and treating the result as exact. That gives only an estimate; the leftover days need counting one by one.
  • Subtracting a holiday that falls on a weekend.
  • Counting the start day when the agreement excludes it, or leaving it out when the agreement includes it.
  • Forgetting that "banking days" or "processing days" may follow a different holiday list than your own.

For a quick answer, use the business days calculator. To move a date forward or back by a number of calendar days, the add days calculator works, and for a plain calendar-day count there is the days between dates calculator.

Try the tools
  • Business Days Calculator: Count how many working days fall between two dates, or find the date that lies a set number of business days from a start date. Weekends are always skipped, and you can add national public holidays for four countries.
  • Add Days Calculator: Pick a start date, enter how many days to add, and get the new date together with its day of the week. A negative number counts backwards.
  • Days Calculator: Use the days calculator to find how many days lie between two dates, or to add days to a date and see the result with its day of the week. Weekdays, weeks and months are reported too.

This article is general information, not professional advice. See our Disclaimer and Editorial Policy.

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