Finance Calc App

Australia GST calculator

Add 10% GST to a price, or back out the GST already included in a gross price — the way it appears on a tax invoice.

By Mitch Duncan Last reviewed Methodology
GST rate: 10.00%

Australian GST is a flat 10% on most goods and services. Basic food, some health, and education are GST-free.

Price before GST
$100.00
GST amount
$10.00
Total incl. GST
$110.00
Effective rate
10.00%

How Australian GST works

Australia's Goods and Services Tax (GST) is a flat 10% on most goods and services. Because the rate is uniform nationwide, the maths is simple: add 10% to a net price, or — since Australian displayed prices must be GST-inclusive — back the GST out of a tax-inclusive total.

Gross = net × 1.10  ·  GST in a gross price = gross ÷ 11

Worked example

A $200 net price plus 10% GST is $20 of tax, for a $220 total. To find the GST already inside a $220 ticket price, divide by 11: that's $20 of GST and $200 net. The "divide by 11" trick works because GST is one-eleventh of any GST-inclusive amount.

GST-free items and registration

Some things are GST-free: most basic food, many health and medical services, and education. Businesses must register for GST once turnover reaches $75,000 a year ($150,000 for non-profits). Registered businesses claim GST credits for the GST in their purchases and report through a Business Activity Statement (BAS).

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Frequently asked questions

How do I add sales tax to a price?
Multiply the net (pre-tax) price by the tax rate to get the tax, then add it back. At a 10% rate, a 100 item carries 10 of tax for a 110 total — or in one step, 100 × 1.10 = 110. The calculator does this automatically in 'add' mode.
How do I remove tax from a tax-inclusive price?
Divide the gross (tax-inclusive) price by 1 plus the rate. At 10%, a 110 total divided by 1.10 is 100 net, leaving 10 of tax. A common mistake is to subtract 10% of the gross price — that gives the wrong answer, because the tax is a share of the net price, not the total.
What's the difference between sales tax, VAT, and GST?
They're all consumption taxes on goods and services, but they differ by country. The US charges state and local sales tax added at checkout; the UK charges Value Added Tax (VAT) at a 20% standard rate; Canada uses GST/HST (and sometimes PST); Australia charges a flat 10% GST. The arithmetic is the same — only the rate and rules differ.
Is the tax rate the same everywhere?
No. The US has no national rate — it's set by each state, county, and city and they stack, so it varies widely by location. The UK's standard VAT is 20% with reduced and zero rates for some goods. Canada's rate depends on the province. Australia is a flat 10%. Always use the rate that applies where the sale happens.
Are some goods tax-free?
Yes. Most systems exempt or reduce tax on essentials. The UK zero-rates most food, books, and children's clothing; Canada zero-rates basic groceries and prescription drugs; Australia makes basic food and many health and education services GST-free; many US states exempt groceries and medicine. This calculator applies one rate, so handle exempt items separately.
Why does dividing by the rate give the wrong tax amount?
Because tax is calculated on the net price, not the gross. If a 110 total includes 10% tax, the tax is 10% of the 100 net price, not 10% of 110 (which would be 11). To split a tax-inclusive total correctly, divide by 1 plus the rate to find the net price first, then subtract.

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