How business days are counted
A business day is a day on which normal commercial business is transacted — Monday to Friday, excluding public holidays. The convention is simple; the counting rules around it are where people come unstuck.
- Business days are Monday through Friday. Saturdays and Sundays are never counted, in any mode.
- Adding days starts on the next working day. Counting begins the day after your start date, so adding 1 business day to a Friday lands on the following Monday. A Friday is never day one of its own count.
- Counting between dates includes both endpoints when they fall on a working day. Monday to Friday the same week is 5 business days, not 4.
- Holiday exclusion optionally removes the eleven US federal holidays. This matters for bank settlement, court filings and government contracts, where "next business day" is defined by statute rather than by habit.
The start-day convention
Every off-by-one business-day error comes down to whether the start day counts. Two rules cover almost all real usage:
| Task | Convention | Example |
|---|
| Add N business days to a date | Start day excluded — counting begins the next working day | Friday + 5 business days = the following Friday |
| Count business days in a span | Both endpoints included if working days | Mon–Fri = 5 business days |
In finance there is a formal vocabulary for what to do when the resulting date is not a business day. Following means roll forward to the next business day. Modified Following means roll forward, but if that crosses into a new month, roll backward instead. Preceding means roll backward. Contracts that specify a convention are far easier to administer than ones that leave it to habit.
Business days in a year
A common year has 365 days, which is 52 weeks plus one day, giving 261 weekdays. Remove the eleven US federal holidays — of which eight to ten fall on a weekday in any given year — and 2026 comes to 250 business days.
| Month (2026) | Weekdays | Business days after federal holidays |
|---|
| January | 22 | 20 |
| February | 20 | 19 |
| March | 22 | 22 |
| April | 22 | 22 |
| May | 21 | 20 |
| June | 22 | 21 |
| July | 23 | 22 |
| August | 21 | 21 |
| September | 22 | 21 |
| October | 22 | 21 |
| November | 21 | 19 |
| December | 23 | 22 |
| Total | 261 | 250 |
The spread is wide enough to matter. November 2026 has 19 usable business days against December's 22, a 16% difference — enough to turn an achievable schedule into a missed deadline if you plan in months rather than days.
Where business-day counting is the rule
| Context | Why business days apply |
|---|
| Securities settlement | US equities settle on a T+1 basis, meaning one business day after the trade — a holiday lengthens the settlement window |
| Banking | Payments and clearing follow the Federal Reserve holiday schedule, so a weekend or holiday due date rolls forward |
| Court filings | Filing deadlines computed under the Federal Rules of Civil Procedure exclude weekends and federal holidays |
| Government contracts | Bid windows and response periods are usually stated in business days precisely to avoid weekend landings |
| Delivery windows | "Ships in 5–7 business days" tells a customer when to expect dispatch, not when it arrives |
Note that trade settlement in the US follows the securities industry calendar rather than the federal holiday list exactly — the two overlap almost completely but not perfectly. If you are working to a settlement deadline, use the exchange calendar for the year.
Three worked examples
1. A project quoted at 10 business days
A contractor quotes 10 business days from Monday 21 September 2026. Ten working days is exactly two weeks when no holiday interferes, so delivery lands on Monday 5 October 2026. The same work quoted in calendar days would have been 10 October — five days later — for no reason other than the wording.
2. A delivery window that crosses Thanksgiving
An order placed on Friday 20 November 2026 with a 5-business-day dispatch window. Thanksgiving falls on Thursday 26 November, so the count skips both the weekend and the holiday: the order ships on Monday 30 November, seven calendar days later rather than five.
If the listing had said "5 days" rather than "5 business days", it would have shipped on 25 November and the customer would have received it before the holiday. This is exactly why ecommerce listings state the convention explicitly.
3. Working back from a filing deadline
A response is due on Friday 15 January 2027 and requires 30 business days of preparation. Set the direction to subtract and 30 business days before that date is Friday 4 December 2026. Add the holiday exclusion — Christmas Day and New Year's Day both fall on weekdays inside the window — and the start date moves to Wednesday 9 December.
Five days of planning error, caught by ticking one box. Planning a long lead time in calendar days is the most common way a fixed deadline is missed.
Tying a deadline to the federal calendar? The 2027 federal holiday calendar lists every observed date, including the two that move.
Sources and standards
How we verify this calculator
Date arithmetic follows the Gregorian calendar and ISO 8601 notation, and runs entirely on calendar dates with no clock time, so no result can shift across a time zone boundary. Holiday exclusion uses the official US federal holiday list for 2026 through 2028, keyed to observed dates rather than nominal ones — a holiday that falls on a Saturday is excluded on the preceding Friday, and one that falls on a Sunday on the following Monday.
Business-day counts and holiday tables last verified: 19 September 2026.
This tool provides calculations, not legal advice. Statutory deadlines can follow their own counting rules, including exclusions and roll-forward conventions that differ from the defaults here.
FAQ
How do I calculate business days from a date?
Start counting from the next working day after your start date and count forward one working day at a time, skipping Saturdays and Sundays. For example, 5 business days from Monday, August 31, 2026 lands on Monday, September 7, 2026.
Does a business day include the start date?
No. When adding N business days to a date, counting starts on the next working day. When counting business days between two dates, both endpoint dates are included if they fall on a working day.
Is Saturday a business day?
In most US and UK business contexts, no — Saturday and Sunday are non-working days. Some industries and countries treat Saturday as a working day, but the standard Monday-to-Friday convention is what this calculator uses.
Can I exclude US federal holidays?
Yes. Tick the holiday option and the calculator also skips US federal holidays such as Labor Day, Thanksgiving, and Christmas Day. The holiday table currently covers 2026 through 2028, using observed dates — so a holiday falling on a weekend is excluded on the weekday it is actually observed.
What is the difference between business days and working days?
Nothing — they are two names for the same thing. UK users usually say "working days" while US users usually say "business days". Both mean Monday to Friday, excluding public holidays.
How long is 10 business days in calendar weeks?
Exactly two weeks when no holidays interfere, because every week contains five business days. A holiday inside the period stretches the calendar span — for example, 10 business days spanning Thanksgiving takes closer to 15 or 16 calendar days.
Do payment terms like Net 30 use business days?
By convention, no — Net 30 means 30 calendar days. But some contracts explicitly state "30 business days", which stretches the deadline to roughly six weeks. Always check the wording; the invoice due date calculator supports both counting modes and shows the difference side by side.
Why do banks count business days differently?
US banks follow the Federal Reserve holiday schedule, so a payment due on a weekend or a bank holiday rolls to the next day the Fed is open. Enable the holiday option above to model this, and note that the Fed schedule is not identical to the federal holiday list in every year.
How many business days are in a month?
Between 19 and 23, depending on the month and the holidays inside it. In 2026 the range runs from 19 in February and November to 23 in July and December, once federal holidays are removed. The month-by-month table above has the full breakdown.
What does T+1 settlement mean?
It means a trade settles one business day after the trade date. US securities moved to T+1 in May 2024, so a trade executed on a Friday settles the following Monday — and a trade before a holiday settles one day later than usual.
Is Saturday a business day anywhere?
Some industries and many countries treat Saturday as a working day or a half day, and some religious calendars make Friday or Saturday the weekend instead. The calculator uses the Monday-to-Friday convention, which covers US and UK commercial practice.
How do courts count filing deadlines?
Under the Federal Rules of Civil Procedure, deadlines are computed by excluding the triggering day, counting intermediate weekends and holidays as normal days, and then rolling forward if the final day is a weekend or holiday. That is not the same as counting only business days, so use this tool as a cross-check rather than a substitute.