Aussie Biz Tools

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Every calculator on the site, what it does, and what it does not do. All of them run entirely in your browser.

Tax — GST

GST calculator

Add 10% GST to a price, or strip GST out of a GST-inclusive total. Shows the GST component both ways and checks it against the ATO's tolerance for rounding, so you can see when a one-cent difference is normal.

 Tax — BAS

BAS due date finder

Pick any date and your reporting frequency and it tells you the period you are reporting on and when the BAS is due — quarterly, monthly or annual, with the online 2-week concession and registered-agent dates applied when they apply.

 Invoicing

Tax invoice generator

Fill in the details, check the compliance list, then download a PDF or print it. The PDF is assembled in your browser — your client names, prices and bank details never touch a server.

 ABN

ABN format checker

Checks whether an 11-digit ABN is correctly formed using the Australian Business Register's mod-89 algorithm, and shows the weighted sum so you can see why. It cannot tell you whether an ABN is registered — that needs ABN Lookup.

 Payroll

Pay cycle converter

Convert pay between weekly, fortnightly, twice-monthly and monthly cycles, anchored on the annual figure. Also works from hourly rate and hours per week, and counts how many pay days actually fall in a financial year.

 Super

Super guarantee calculator

Super payable at the current 12% rate, with the maximum contribution base applied. Handles the 1 July 2026 Payday Super change, including the shift from a quarterly cap to an annual one.

 Pricing

Markup & margin calculator

Work out a quote price from cost plus markup, find the margin you would actually earn, or start from a target margin. Shows markup and margin side by side so the difference between them is obvious.

 Dates

Australian public holidays by state

Public holidays for every state and territory, plus the next one coming up and how many days away it is. Data is bundled, so the page keeps working with no network connection.

What is not here — and why

These are the questions people ask for and that this site deliberately does not answer:

  • Income tax estimates. A take-home pay figure depends on your residency, deductions, HELP debt, offsets and private health cover. A calculator that ignores those is worse than none. The current rates are listed on the about page so you are not misled by old ones.
  • Whether an ABN is registered. That is a live lookup, not arithmetic. Use ABN Lookup.
  • Payroll award interpretation. Penalty rates, loadings and award classifications are legal questions. See the Fair Work Ombudsman.
  • Filing or lodging anything. Nothing here talks to the ATO. It cannot lodge, pay or register anything.
Reserved space

Held for our own spreadsheet templates — our spreadsheet templates. No third-party script is loaded here.

GST calculator

Free GST calculator for Australian business. Add 10% GST to a price or remove GST from a GST-inclusive total, with the r

BAS due date finder

Find the due date for any BAS period: quarterly (28 Oct, 28 Feb, 28 Apr, 28 Jul), monthly (the 21st) or annual (31 Octob

Tax invoice generator

Create an Australian tax invoice and download it as a PDF. Checks the details the ATO requires, handles GST per line, an