GST calculator (Australia)
ReadyAdd 10% GST to a price or find the GST included in a GST-inclusive price (one-eleventh), rounded to the nearest cent.
Rules applied
Checked on 2026-10-20 · tax year 2026–27
GST rate 10%.
Every rate and threshold used in the calculation was checked against the official sources above.
How to use
- Choose whether to add GST to a price or work out the GST included in a total.
- Enter the amount.
- Read the GST, the price excluding GST and the GST-inclusive price.
Formula
- Add GST: GST = price × 10%, total = price + GST
- GST included in a price = total ÷ 11
- Price excluding GST = total − GST
Worked example
$250.00 + GST = $275.00 (GST $25.00). $110.00 including GST → GST $10.00, price excluding GST $100.00.
FAQ
Does every sale include GST?
No. GST is a 10% tax on most goods and services, but GST-free sales and input-taxed sales don’t include it – the ATO explains which sales fall into each group. Businesses only charge GST if they are registered – generally when GST turnover is $75,000 or more.
Why divide by 11?
A GST-inclusive price is 110% of the price before GST, so the GST part is 10/110 = 1/11 of the total.
Data sources
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