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Working days calculator for construction contracts

Count business days between two dates, or add business days to a date, with Australian public holidays by jurisdiction, and see exactly which days were skipped.

What do you need?

From

State or territory

Construction calendar

RDO calendar

An approximation of a typical pattern. Use your own EBA calendar for anything contractual.

Inclement weather allowance

Days lost per month, if you want a weather-adjusted date as well.

Exclude the December–January industry shutdown

Shutdown starts (MM-DD)

Resumes after (MM-DD)

Enter both dates. The end date must be after the start.

Contract days are not calendar days

Every contract and every Act defines its own day. Security of payment legislation in New South Wales excludes 27 to 31 December from business days; Queensland excludes 22 to 24 December, 27 to 31 December and 2 to 10 January. Standard contract forms mostly count calendar days. EBAs add RDOs that no statute knows about.

This calculator counts weekends, public holidays and whatever you switch on above. It does not know your contract. For a statutory deadline, use the tool built for that Act.

Public holidays cover national and principal state holidays; local show days and one-off declared holidays are not included. RDO patterns are an approximation of common practice, not your EBA. For a statutory deadline under security of payment legislation, use the calculator built for that Act, the definition of business day differs.

Why construction counts days differently

Construction contracts and legislation use several different day counts, and they are not interchangeable. Calendar days include everything. Business days exclude weekends and public holidays. Working days under a particular contract may also exclude rostered days off or an inclement weather allowance.

Getting the basis wrong is not a rounding error. A notice period counted in calendar days when the contract says business days can be a week out, and a week is frequently the difference between a valid notice and a barred one.

The first question on any deadline is therefore not when, but on what basis, and the answer is in the contract or the Act, not in convention.

Public holidays are jurisdictional, and that is the trap

There is no single Australian public holiday calendar. Each state and territory declares its own, and the differences are real: Labour Day falls in different months, some jurisdictions have holidays others do not, and substitute days for holidays falling on a weekend are handled differently.

A project in one state administered by a head office in another will get this wrong unless somebody is deliberate about which calendar applies. It is usually the place where the work is performed or where the notice must be served, but the contract may say otherwise.

This calculator asks which jurisdiction and shows which specific days it excluded, so the count can be checked rather than trusted.

What this calculator does not know

It carries national holidays plus the principal state and territory holidays. It does not carry local show days, regional holidays, the AFL Grand Final Friday, or construction industry rostered days off.

Those matter. A regional show day is a public holiday in that district and will shift a deadline. Industry RDOs shift programme dates even where they do not shift legal ones.

The tool shows its working precisely so you can add what it does not know. Treat the output as a well-documented starting point rather than a final answer, particularly where a limitation period is involved.

When the answer really matters, check it twice

Most day counts are administrative and an error is recoverable. A few are not: security of payment deadlines, notice periods that operate as a condition precedent, and limitation periods.

For those, count it, have someone else count it independently, and diarise the deadline with a buffer rather than on the day. A deadline hit at 4:58pm on the last day is a deadline you got lucky on.

Our security of payment calculator handles the statutory timeframes specifically, because those Acts exclude particular days around Christmas and New Year that a general business-day count will not catch.

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