How do I calculate GST in Australia?

Australian GST is a flat 10%. To add GST to a GST-exclusive price, multiply by 0.10 — a $100 item attracts $10 GST for a $110 total. To find the GST inside a GST-inclusive price, divide the total by 11 — a $110 price contains $10 GST.

Why do you divide by 11 to find GST?

A GST-inclusive price is 110% of the base price — 100% base plus 10% GST. The GST is therefore 10/110 of the total, which simplifies to one eleventh. Dividing any GST-inclusive amount by 11 gives the exact GST component.

When does a business have to register for GST?

You must register for GST when your business's GST turnover reaches $75,000 or more in a 12-month period ($150,000 for non-profits). Taxi and ride-share drivers must register regardless of turnover. Below the threshold, registration is optional.

What is a BAS and how does GST reporting work?

A Business Activity Statement (BAS) is the form GST-registered businesses lodge with the ATO — usually quarterly — to report GST collected on sales and GST credits on purchases. You pay the ATO the difference, or receive a refund if your credits exceed the GST you collected.

§ — Tax

GST: add 10%, or divide by 11 to take it out.

Q: What items are GST-free in Australia?

GST-free items include most fresh food (fruit, vegetables, meat, bread, milk), most health and medical services, most education courses, childcare, water and sewerage, and exports. Processed and prepared foods like confectionery, soft drinks and restaurant meals do attract GST.

Australia's GST has been a flat 10% since it began in July 2000. Enter any amount and we'll show the GST component, the price excluding GST, and the price including GST — whichever direction you're working in.

Updated · Jul 2026·Source: ato.gov.au·Read · 3 min

Your inputs

What do you want to do?

Start from a GST-exclusive price and add 10%.

Amount excluding GST

Inputs local. Nothing sent anywhere.

The result

GST component · 10% added

$10.00

Added to your ex-GST price at the flat 10% rate

Price excluding GST: $100.00
Price including GST: $110.00

$100.00 × 10% = $10.00 GST, for a total of $110.00 including GST.

How GST works — and why you divide by 11

The Goods and Services Tax is a broad-based 10% tax on most goods, services and other items sold or consumed in Australia. It was introduced on 1 July 2000 and the rate has never changed.

Adding GST is simple: multiply the GST-exclusive price by 10%. A $100 service attracts $10 of GST, so the customer pays $110.

Working backwards trips people up. The GST inside a GST-inclusive price is not 10% of the total— it's one eleventh. A GST-inclusive price is 110% of the base, so the GST share is 10/110, which simplifies to 1/11. Divide any GST-inclusive amount by 11 and you have the exact GST component: a $110 invoice contains $10 of GST, not $11.

Not everything attracts GST. GST-free supplies include most fresh food (fruit, vegetables, meat, bread, milk), most health and medical services, most education courses, childcare, water, and exports. The line can be fine — a plain bread roll is GST-free, but a hot pie or a soft drink is taxable.

GST at a glance

Item	GST?
Fresh food (fruit, veg, bread, milk)	GST-free
Health & medical services	GST-free
Education courses	GST-free
Restaurant meals & takeaway	10%
Electronics, clothing, fuel	10%
Professional services	10%

Source: ato.gov.au · GST

Registration, the $75,000 threshold, and the BAS

A business must register for GST once its GST turnover reaches $75,000 in a rolling 12-month period — $150,000 for non-profit organisations. Taxi and ride-share drivers must register from their first dollar, regardless of turnover. Below the threshold, registration is optional: registering lets you claim GST credits on business purchases, but it also means charging your customers 10% more and lodging activity statements.

Once registered, you report GST on a Business Activity Statement (BAS) — quarterly for most small businesses. The mechanics are simple: you report the GST you collected on sales, subtract the GST credits on your business purchases, and pay the ATO the difference. If your credits exceed the GST you collected, the ATO refunds you.

A practical habit: because the GST you collect belongs to the ATO, not to you, many accountants recommend setting aside 1/11 of every GST-inclusive sale in a separate account as it comes in — exactly the divide-by-11 figure this calculator produces — so the quarterly BAS bill is never a surprise.

§ Letters & replies

GST, answered.

Common questions about GST in Australia.

Why divide by 11 and not take 10%?+ open

A GST-inclusive price is 110% of the base price, so the GST is 10/110 of the total — one eleventh. Taking 10% of a GST-inclusive price overstates the GST: 10% of $110 is $11, but the actual GST is $10.

Has the GST rate ever changed?+ open

No. GST has been 10% since it was introduced on 1 July 2000. Changing the rate requires the agreement of all state and territory governments as well as federal legislation.

Which items are GST-free?+ open

Most fresh food, most health and medical services, most education courses, childcare, water and sewerage, precious metals, and exports. Prepared foods — restaurant meals, takeaway, confectionery, soft drinks — are taxable even though they're food.

Do I have to register for GST?+ open

Only once your GST turnover reaches $75,000 in a 12-month period ($150,000 for non-profits), or immediately if you drive a taxi or ride-share. Below that, it's optional — worth it mainly if you have significant GST credits to claim on purchases.

How often do I lodge a BAS?+ open

Quarterly for most businesses. Monthly is required if GST turnover is $20 million or more (and optional below that). Businesses under $75,000 that registered voluntarily can report annually.

Is this calculator a substitute for tax advice?+ open

No. It applies the flat 10% rate and the divide-by-11 rule — it can't tell you whether a particular supply is taxable, GST-free or input-taxed. For classification questions or BAS obligations, check ato.gov.au or ask a registered tax or BAS agent.

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GST: add 10%, or divide by 11 to take it out.

How GST works — and why you divide by 11

Registration, the $75,000 threshold, and the BAS

GST, answered.

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