Australian GST Calculator
Add 10% GST, or divide by 11 to pull the GST out of a GST-inclusive price.
This Australian GST calculator opens on the flat 10% rate, so you can add GST to a quote or find the GST already sitting inside a price without changing a setting. Type the dollar figure, choose add or remove, and the GST-exclusive amount, the GST and the GST-inclusive total appear together.
Australia's rate makes the reverse calculation unusually tidy. Because 10% GST means the tax is one-eleventh of the inclusive price, you divide a GST-inclusive total by 11 to get the GST — $110 contains exactly $10 of GST. That single fact answers most of what Australians look up, and it is the reason you should never subtract 10% from an inclusive figure: $110 minus 10% is $99, which is simply the wrong number.
GST has applied at 10% since 1 July 2000 and is administered by the ATO. Every calculation runs locally in your browser with nothing uploaded, and the country selector switches the tool to New Zealand, Singapore or anywhere else if you trade across the Tasman or beyond.
How to work out GST in Australia
- Choose whether you are adding GST to a GST-exclusive price or removing it from a GST-inclusive one.
- Enter the dollar amount.
- Leave the rate at 10% — Australia has a single GST rate with no reduced bands.
- Read the ex-GST amount, the GST and the inclusive total side by side.
- Sanity-check the result: on any inclusive figure, the GST should be exactly one-eleventh of it.
The divide-by-11 rule, and why it works
Adding GST multiplies a price by 1.1, so a $100 job becomes $110. Reversing that means dividing by 1.1, which gives $100 back and leaves $10 of GST. Since the tax is $10 out of $110, it is one-eleventh of the inclusive amount — hence the rule every Australian bookkeeper knows: to find the GST in a GST-inclusive price, divide by 11. A $2,750 inclusive invoice contains $250 of GST; a $99 inclusive receipt contains $9.
The mistake the rule prevents is subtracting 10%. Ten per cent of $110 is $11, not $10, because the tax was calculated on the smaller $100 base and is therefore a smaller fraction of the total. Subtracting overstates the GST by about 10% on every line it touches, which is enough to distort a BAS. The companion shortcut is that the ex-GST amount is ten-elevenths of the inclusive figure — multiply by 10 and divide by 11.
GST-free supplies: food, health and education
Australia does not use reduced rates; instead a defined list of supplies is GST-free, meaning no GST is charged but the supplier still claims back the GST on related costs. The big categories are most basic food, most medical and health services and many medical aids, most education courses and course materials, childcare, water and sewerage, and exports. That is why the total on a supermarket receipt is rarely a clean eleventh — the trolley usually mixes GST-free groceries with taxable items.
The food rules are famously fiddly at the edges. Plain bread and milk are GST-free; food marketed as prepared, confectionery, savoury snacks, bakery products of certain kinds and hot takeaway food are taxable, and the same ingredient can flip depending on how it is sold. There is also a separate 'input taxed' category — financial supplies and residential rent — where no GST is charged and no credits can be claimed, which is a worse outcome for the supplier than GST-free. Check the ATO's food and health lists rather than guessing.
The $75,000 threshold and who must register
You must register for GST once your GST turnover reaches A$75,000 or you expect it to, tested on a rolling twelve-month basis looking both back and forward. Non-profit organisations get a higher limit of A$150,000. The turnover test uses gross business income excluding GST, not profit, so a sole trader with high costs can be well over the line while earning modestly.
Two rules override the threshold entirely. Taxi, limousine and ride-sourcing drivers must register from the first fare no matter how little they earn — a trap for anyone driving part-time on a platform. Businesses wanting to claim fuel tax credits must also register. Registration is optional below the threshold and can be worth it when your customers are themselves registered businesses, since they simply claim back what you charge, while your own input tax credits become recoverable.
ABNs, tax invoices and the $82.50 rule
Registration is tied to an Australian Business Number, and your ABN must appear on your tax invoices. A valid tax invoice shows that it is intended to be a tax invoice, your identity and ABN, the date, a description of what was sold, the GST amount or a statement that the total price includes GST, and — for sales of $1,000 or more — the buyer's identity or ABN. Without a compliant invoice a customer generally cannot claim the credit.
The threshold most people remember is $82.50: for purchases at or below that amount including GST, you can claim a credit without holding a full tax invoice, provided you have some other record such as a receipt or bank statement. Above it, you need the invoice. Another everyday trap is the no-ABN withholding rule, which requires a payer to withhold from a supplier who does not quote an ABN. Confirm the current figures on the ATO website before building them into a policy.
Lodging your BAS
GST is reported on the Business Activity Statement. Most small businesses lodge quarterly, businesses with a GST turnover of A$20 million or more must lodge monthly, and some voluntarily registered businesses below the threshold can elect to report annually. The BAS nets your GST on sales against your GST credits on purchases, and the difference is either paid to the ATO or refunded to you.
Two reporting choices shape the numbers. Cash accounting recognises GST when money moves and is available to smaller businesses; accruals accounting recognises it when the invoice is issued, which can mean paying GST before the customer has paid you. Separately, the simpler BAS reporting method reduces the fields most small businesses complete. Lodgement dates differ between quarterly and monthly cycles and are extended for lodgements made through a registered agent — take them from the ATO or your agent, not from memory.
Imports, digital products and low-value goods
GST applies to most goods imported into Australia. Since 2018 the low-value imported goods rules have required overseas sellers, marketplaces and re-deliverers above the registration turnover to charge GST at the point of sale on goods valued at or below the customs threshold, so an item bought from an overseas website often arrives with Australian GST already paid. Goods above that value are taxed at the border instead, through customs.
The parallel rules for imported services and digital products — streaming subscriptions, software, e-books, online courses — mean overseas suppliers register and charge GST to Australian consumers. If you are a registered business buying such services for business use, you may need to check whether the supplier charged GST or whether a reverse charge applies to you. These rules are why the GST on a foreign invoice is worth reading carefully before assuming it is out of scope.
Common GST errors, and the limits of this tool
The frequent mistakes are recognisable: subtracting 10% instead of dividing by 11; treating every grocery line as taxable when much of it is GST-free; claiming credits without a valid tax invoice; claiming the GST portion of a purchase used partly for private purposes without apportioning; and confusing input-taxed supplies with GST-free ones, which have opposite consequences for credits. Rounding also matters — calculating GST line by line and summing can differ by a cent or two from calculating it once on the total, and the ATO accepts a consistent approach.
This calculator handles the 10% arithmetic and nothing more. It does not decide whether your supply is taxable, GST-free or input taxed, apportion mixed use, handle the margin scheme on property, or work out your reporting method. Rates, thresholds and reporting rules can change and specific goods are treated differently, so confirm anything you will lodge or price on with the ATO or a registered tax agent. This page is information, not tax advice.
Frequently asked questions
How do I find the GST in a GST-inclusive price?
Divide the inclusive total by 11. A $110 price contains $10 of GST and $100 ex-GST. Never subtract 10% — that gives $99 and overstates the tax.
How do I add GST to a price?
Multiply the GST-exclusive amount by 1.1, or work out 10% and add it on. A $450 quote becomes $495 including GST, with $45 of GST.
When do I have to register for GST in Australia?
Once your GST turnover reaches A$75,000, or A$150,000 for a non-profit, tested over a rolling twelve months. Taxi, limousine and ride-sourcing drivers must register regardless of turnover.
Which things are GST-free?
Most basic food, most medical and health services, most education and childcare, water and sewerage, and exports. The food rules are detailed at the edges — prepared, hot and confectionery items are usually taxable, so check the ATO lists.
How often do I lodge a BAS?
Most small businesses lodge quarterly. Monthly lodgement is required at a GST turnover of A$20 million or more, and some voluntarily registered businesses can report annually. Due dates differ and are extended through a registered agent.
Can I rely on this when preparing my BAS?
Use it for the arithmetic only. Whether a supply is taxable, GST-free or input taxed, how credits are apportioned, and which reporting method applies to you are matters for ATO guidance or a registered tax agent.