What business days are and why you count them
Business days (also called working days) are the days from Monday to Friday — the days courts, banks, government offices and most companies actually operate. They matter whenever a deadline is written “in business days” instead of calendar days: the reply to a legal notice, a “net 30 working days” invoice, a refund window, or a shipping estimate.
The catch is that weekends break the count. From Monday the 6th to Monday the 20th there are 14 calendar days but only 10 business days, because two Saturdays and two Sundays fall in between. And any public holiday that lands on a weekday has to come out too. This calculator handles all three: it counts Monday through Friday, ignores weekends, and subtracts whatever holidays you paste in.
How to use it
- Pick the start date and the end date. Order doesn’t matter — if you swap them, the tool runs from the earlier date to the later one.
- Check or uncheck include the last day. The first day is always counted; the last day counts only when the box is ticked.
- Optionally paste holidays into the box, one
YYYY-MM-DDdate per line. Any that fall on a weekday inside the range are removed. - Read the business days on the dark card, plus weekend days, total days, and holidays removed.
How the count works
The tool walks the range one day at a time. Each date is built in UTC with Date.UTC(year, month, day) and its weekday is read with getUTCDay, which returns 0 for Sunday and 6 for Saturday. Working in UTC keeps a time zone from shifting the date a day backward or forward.
For every day in the range:
- If it is a Saturday or Sunday, it adds to weekend days.
- If it is a weekday and appears in your holiday list, it adds to holidays removed.
- Otherwise, it adds to business days.
So total days = business days + weekend days + holidays removed.
Worked example
Take a full month of November 2026: from Monday, November 2 to Monday, November 30, with “include the last day” checked. That span is 29 total days. The weekends are the Saturdays and Sundays of the 7th–8th, 14th–15th, 21st–22nd and 28th–29th, which is 8 days, leaving 21 business days.
Now add a holiday. Thanksgiving 2026 falls on Thursday, November 26. Paste 2026-11-26 into the box and that Thursday moves from business days to holidays removed, so the result drops to 20 business days.
Business days by period (2026)
| Period | Total days | Business days |
|---|---|---|
| Two-week sprint (Mon 2 to Fri 13 Nov) | 12 | 10 |
| November 2 to November 30 | 29 | 21 |
| July 2026 (full month) | 31 | 23 |
| Full year 2026 | 365 | 261 |
Frequently asked questions
Should I include the last day?
It depends on how your deadline is phrased. If it says “you have 10 business days starting Monday,” you usually count both ends — tick the box. If you’re measuring a duration from one date until another, the final day is often not counted — untick it. The tool always includes the first day.
Which holidays should I add?
Use your country’s or company’s official calendar. Only holidays that land on a weekday inside the range matter; ones on a Saturday or Sunday were already excluded, so there’s no need to paste them. Watch for observed dates too: in the US a Saturday holiday is often observed the Friday before, and that observed date is the weekday that actually removes a working day.
How many business days are in a year?
A common year of 365 days usually has 261 business days and 104 weekend days, before removing any holidays. The exact figure moves by a day depending on which weekday the year starts on and whether it’s a leap year, but 261 is the typical value for 2026.
Does the calculator know holidays automatically?
No. To avoid mixing up countries and years, it ships with no built-in calendar and only removes the dates you paste. That keeps it accurate whether you’re in the Dominican Republic, Mexico, Spain or working off a private company calendar.
Why UTC instead of my local time?
Because a calendar date like 2026-11-26 has no time attached. If it were read in your local zone, users west of Greenwich could see it slip to November 25 and count the wrong weekday. Pinning everything to UTC midnight keeps the 26th a Thursday for everyone.