Free tools for running an Australian small business
Eight calculators that do the jobs you actually get stuck on — GST, BAS dates, a tax invoice you can hand a customer, ABN checks, pay cycles, super, markups and public holidays. Every rate is dated and linked to the official source. No account, no email, no trackers: the arithmetic happens in your browser.
GST calculator
Add GST to a price or pull it back out of a GST-inclusive total, with the rounding shown line by line.
BASBAS due date finder
Quarterly, monthly or annual — the due date for any period, including the online 2-week concession and agent program dates.
InvoicingTax invoice generator
Build a compliant tax invoice and download it as a PDF. Generated in your browser — nothing is uploaded.
ABNABN format checker
Run the ATO's mod-89 check-digit algorithm and see the working, step by step.
PayrollPay cycle converter
Weekly, fortnightly, twice-monthly and monthly — convert a figure across cycles and see the annual anchor.
SuperSuper guarantee calculator
What you owe at 12%, including the maximum contribution base and the 1 July 2026 Payday Super change.
PricingMarkup & margin calculator
Quote from cost plus markup, or work backwards from the margin you need to hit.
DatesAustralian public holidays
Public holidays by state and year, plus the next one coming up. Works offline from bundled open data.
Why this site exists
Most Australian small-business calculators online are either buried inside accounting software you have to sign up for, wrapped in three advertising trackers, or quietly out of date — still showing a 9.5% super rate two years after it changed.
These tools are the opposite by design:
- Every rate is dated and linked. You can see where 12% or 28 February came from and check it yourself against the ATO page.
- Nothing leaves your browser. No analytics, no cookies, no third-party scripts of any kind. The invoice generator builds the PDF on your own machine.
- The maths is tested. Every calculator is checked against known cases by a test script that runs the same code the page runs — including the ATO's own worked ABN example.
- Known limitations are stated. Where a rule has an exception we cannot know about (a substituted accounting period, a rate that changed mid-year), the tool says so instead of guessing.
General information, not advice. These calculators do arithmetic using published rates. They do not know your business, your registrations or your circumstances. For anything with a consequence — a BAS position, a super obligation, an employment decision — check with your accountant or the ATO.
This slot is held for our own small-business spreadsheet templates: our spreadsheet templates. They are being checked now, so the link goes to a page that says what is coming rather than to anything for sale. It is a placeholder: no third-party script, no ad network and no tracking is loaded on this page.
Built by hand, in plain HTML
There is no framework, no build server and no external font on this site. It is static HTML, one stylesheet and a handful of small JavaScript files, which is why it loads in well under a second on a phone with one bar of signal. Calculator code is shared with the test suite, so what runs in your browser is the same code that gets checked.
See About & sources for the full list of official sources, the date each was checked, and the licence terms for the public holiday data.
Related tools
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