GST Calculator
Australian goods and services tax, 10%
How GST works in Australia
Goods and Services Tax is a flat 10% tax on most things sold or consumed in Australia. There are only two sums you ever need. To add GST, multiply the price by 1.1. To find the GST already inside a total, divide the total by 11.
The second one catches people out constantly, because the instinct is to take 10% off the total instead. That gives the wrong answer every time. 10% of $110 is $11, but the GST inside $110 is $10. The reason is that the 10% was added to the smaller number, not the bigger one, so it is 10% of the ex-GST price and about 9.09% of the GST-inclusive price. Dividing by 11 gets you there in one step.
Adding GST: worked examples
| Price excluding GST | GST (10%) | Price including GST |
|---|---|---|
| $50 | $5 | $55 |
| $100 | $10 | $110 |
| $250 | $25 | $275 |
| $1,000 | $100 | $1,100 |
| $5,000 | $500 | $5,500 |
This is the direction you work in when you are quoting a customer. You know what you need to earn on the job, and GST goes on top.
Removing GST: worked examples
| Total paid | GST inside it | Price excluding GST |
|---|---|---|
| $55 | $5.00 | $50.00 |
| $110 | $10.00 | $100.00 |
| $275 | $25.00 | $250.00 |
| $1,100 | $100.00 | $1,000.00 |
| $5,500 | $500.00 | $5,000.00 |
This is the direction you work in when you are reading a receipt, filling in a business activity statement, or working out what a job was really worth to you after the GST is handed on.
Not everything has GST on it
Three categories matter, and they behave differently:
- Taxable. Most sales. GST is charged, and the business can claim back the GST on its own purchases.
- GST-free. No GST is charged, but the business can still claim back the GST it paid on inputs. Basic food, most medical and health services, education courses, and childcare sit here.
- Input taxed. No GST is charged and the business cannot claim the GST on related purchases. Residential rent and most financial supplies sit here.
The line inside "basic food" is narrower than people expect. Plain bread, milk, meat and fresh produce are GST-free. Prepared and restaurant food, takeaway, confectionery, snacks and most drinks other than milk are taxable. That is why a supermarket receipt has GST on some lines and not others.
When a business has to register for GST
Registration is compulsory once your GST turnover reaches $75,000 in a 12 month period, measured on what you have turned over in the last 12 months or expect to turn over in the next 12. It is not a financial year test, and it is not about profit. Non-profit organisations get a higher threshold, and taxi and ride-sourcing drivers must register from their first dollar regardless of turnover.
Below $75,000 registration is optional. Registering voluntarily lets you claim GST credits on your purchases, which can be worth it if you buy a lot of equipment or your customers are themselves GST-registered businesses that do not care about the GST on your invoice. It also commits you to charging GST on every sale and lodging activity statements, which is a real administrative cost if your customers are households.
Source: ATO, registering for GST. Checked 21 August 2026. TaxSnap is a calculator, not a tax agent: see the disclaimer and where every figure comes from.
Tax invoices and claiming GST credits
If you are registered, you claim back the GST you paid on business purchases as an input tax credit. Two document rules govern that:
- For purchases of $82.50 or less including GST, you do not need a tax invoice, though you still need some record of the purchase.
- Above that you need a valid tax invoice, and for sales of $1,000 or more it must also identify the buyer.
You can only claim the GST that was actually charged. A GST-free purchase has no GST in it to claim, and a supplier who is not registered cannot charge you GST at all. If an invoice from an unregistered supplier shows a GST line, that is a problem with the invoice, not a credit you can claim.
Reporting and paying it
GST is reported on a business activity statement, usually quarterly, monthly if your turnover is large enough, and annually for some voluntary registrants. You pay the GST you collected minus the GST you paid, so in a quarter where you bought more than you sold you can be owed a refund.
The practical trap is cash flow. The GST you charge is never yours: you are collecting it for the ATO and it will be due at the end of the quarter. Businesses that treat a GST-inclusive payment as income and spend it all are the ones that get caught short on the BAS. Moving the GST portion into a separate account the day you are paid is the simplest fix, and it is what this calculator's "remove GST" mode is for.
Frequently Asked Questions
How do I calculate GST in Australia?
Add GST by multiplying the price by 1.1. To find GST already included in a total, divide the total by 11. The GST rate is a flat 10%.
How do I remove GST from a total?
Divide the GST-inclusive total by 11 to get the GST amount, then subtract it. For example $110 divided by 11 is $10 of GST, leaving $100 excluding GST.
Why can't I just take 10% off the total to remove GST?
Because the 10% was added to the smaller, ex-GST price. Taking 10% off $110 gives $99, which is wrong. The GST inside $110 is $10, so the correct answer is $100. Dividing by 11 gets it right in one step.
What is the GST rate in Australia?
The GST rate is a flat 10% on most goods and services. Some things are GST-free, including basic food, most medical and health services, education and childcare.
At what turnover do I have to register for GST?
You must register once your GST turnover reaches $75,000 over a 12 month period, looking either backwards or forwards. Non-profits have a higher threshold and taxi or ride-sourcing drivers must register from the first dollar.
Do I need a tax invoice to claim GST?
Not for purchases of $82.50 or less including GST, though you still need a record. Above that you need a valid tax invoice, and for purchases of $1,000 or more the invoice must also identify the buyer.