How business days are counted in Australia

What counts as a business day, and who decides

A business day — the same thing as a working day in most Australian documents — is a day on which ordinary commerce is expected to happen. In practice that means Monday to Friday, excluding any day that is a public holiday in the jurisdiction whose calendar governs the deadline. Nothing about that definition is set nationally. The weekday part is convention, and the holiday part is legislated separately by each state and territory.

That leaves three inputs to every business-day question, and it is worth naming them explicitly, because leaving any of them implicit is how two people reach different answers from the same document.

• The working week. Monday to Friday unless something says otherwise. A retailer trading seven days a week still counts business days the ordinary way when reading a contract.
• The holiday calendar. Which state or territory’s public holidays apply, since they differ. Our guide to Australian public holidays sets out which holidays exist where and how substitute days are worked out.
• The counting convention. Whether the first day, the last day, or both are included in the total.

Get all three right and business-day arithmetic is mechanical. Get one wrong and you are usually out by exactly one day, which is the amount most disputes are about.

Counting between two dates is not the same as adding days to one

People use “ten business days” to mean two genuinely different calculations, and the words do not distinguish them. The first is a measurement: two dates are already fixed, and you want to know how many working days separate them. The second is a projection: one date is fixed, a number of working days is specified, and you want the resulting date.

Counting between:  start date + end date  →  number of business days
Adding to a date:  start date + number    →  end date

These are not inverses of each other under the usual conventions, and that is the trap. If you count the business days between two dates inclusively and get twelve, then adding twelve business days to the start date does not land on your end date — it overshoots, because the inclusive count already spent one of its twelve on the start date itself while the addition does not.

The wording in the source document usually tells you which operation is intended. “Within ten business days of receiving this notice” is an addition: it produces a deadline. “There were only ten business days between exchange and settlement” is a count: it measures a span that has already been defined at both ends.

Inclusive counting and the off-by-one argument it starts

Inclusive counting means both endpoints are part of the total. Monday to Friday of the same week is five business days inclusively, and four if you count only the days after Monday. Neither is wrong in the abstract; what matters is that everyone uses the same one.

OzCalc follows the spreadsheet conventions, because those are what most people are implicitly comparing against.

Legal drafting has its own vocabulary for the same problem. “Clear days” signals that both the first and last day are excluded. A period expressed as running “from” a date usually excludes that date, while “on and from” includes it. And a deadline of “not less than 5 business days before” a meeting requires five full working days in between, not five days counted from the notice. If your document uses any of these phrases, follow the document rather than a general rule.

Counting a real span: a Christmas shutdown in New South Wales

The end of the year is where every complication arrives at once: weekends, national holidays, a substitute weekday, and a span that crosses into the next calendar year. Working one through by hand shows what the calculator is doing, and the procedure is always the same four steps.

1. Count the calendar days from the start date to the end date, including both.
2. Subtract the Saturdays and Sundays in that range.
3. List the public holidays in the range for the jurisdiction that applies, and subtract only those that fall on a weekday — a holiday on a Saturday has already been removed.
4. Include any substitute weekday holidays, because those are the ones that quietly cost a working day.

The same span shows the inclusive-versus-additive gap in one number. Adding ten business days to Monday 21 December 2026 with the NSW calendar lands on Thursday 7 January 2027 — but the inclusive count from 21 December to 7 January is eleven, not ten. Both results are correct under their own convention, and quoting one against the other is how a deadline argument starts.

Why the state you choose changes the answer

Public holidays are gazetted by each state and territory, so a span that crosses a state-specific holiday counts differently depending on the calendar you apply. Early October 2026 is a clean illustration: Monday 5 October is Labour Day in New South Wales, the ACT and South Australia, and the King’s Birthday in Queensland, while Victoria, Western Australia, Tasmania and the Northern Territory all work that day.

Across a whole year the differences compound. 2026 contains 261 weekdays. Applying the NSW calendar leaves 253 working days, Victoria 252 and the ACT 251, because the ACT observes Canberra Day and Reconciliation Day on top of the shared set. The workdays per year calculator produces that figure for any jurisdiction, which is more useful than a national average when you are budgeting contractor days or leave.

The calculator also offers a national-holidays-only setting, and it is worth understanding what it means. Choosing it excludes the eight holidays observed everywhere and nothing else, which gives 255 working days in 2026 — more than any actual state or territory. It is the right choice for a deliberately jurisdiction-neutral estimate, and the wrong choice if anyone is going to rely on the date.

Where the count matters, and when the contract overrides it

Business days appear wherever a deadline needs to ignore weekends. The common Australian contexts each have their own quirks.

• Property settlement. A contract of sale nominates a settlement period, and whether it is expressed in calendar days or business days changes the date materially over a Christmas or Easter break.
• Cooling-off periods. Residential sale cooling-off rights are set by state legislation and are typically expressed in business days, which is one reason they differ in length between states.
• Notice periods. Notices to remedy, rent increase notices and termination notices often run in business days, and service rules can add further days depending on how the notice was delivered.
• Payment terms. Invoice terms such as “net 30” are usually calendar days, while “within 10 business days” is not — reading one as the other is a fortnight of error.
• Employment and pay. Public holidays affect entitlements and penalty rates as well as counting, and the Fair Work Ombudsman is the authority for what an employee is owed on one.

In all of these, a definition in the document beats any general rule. Commercial agreements routinely define “business day” for their own purposes, and the definitions are not interchangeable. A clause may specify a day banks are open for general banking business in a named city, which can exclude a bank holiday that is not a general public holiday, and which ties the answer to that city’s calendar even if neither party is there. Others exclude a nominated shutdown period outright. Read the definitions clause before counting anything.

The holidays a general tool will not have

Even with the right jurisdiction selected, some genuinely observed non-working days are invisible to a national calculator. Regional agricultural show days are declared locally and differ from town to town. Some racing carnival and local government holidays apply to a single district. Part-day holidays — an evening on Christmas Eve or New Year’s Eve, for example — affect pay and trading hours without removing a whole working day. Where any of these could decide a payroll or contractual outcome, check the state or territory source that declares them.

What the OzCalc business days calculator does and does not model

The business days calculator runs in three modes: count between two dates, add business days, and subtract business days. It walks the calendar one day at a time, skipping Saturdays, Sundays and any date in the holiday set for the jurisdiction you selected, which is the same holiday table the public holiday calendar displays. Because the holidays are generated from dating rules rather than typed in year by year, it works for future years without needing a new list.

• It treats every weekday equally. Shift work, rostered days off, part-time patterns and enterprise agreements are outside its scope.
• It counts whole days only, so part-day holidays leave the day intact.
• It does not include local show days, regional holidays or bank holidays, and it cannot know about a shutdown defined in your contract.
• It has no notion of a cut-off time. If a deadline is 5pm on the tenth business day, the calculator gives you the date and you supply the hour.
• It applies one jurisdiction to the whole span. A deal that changes governing jurisdiction part-way through needs to be split into two calculations.

For spans where weekends and holidays are not the point, the days between dates calculator gives the plain calendar difference along with weekday and weekend totals, which is the right tool for measuring an age or a raw duration rather than a working-day deadline.

Common questions