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GST calculator

Work out GST, the GST-exclusive amount and the GST-inclusive amount for a wholly taxable supply at 10%, rounded once to cents.

Published 20 September 2026. Last reviewed 27 September 2026.

GST inputs
Enter the inputs and calculate.

Sources applied

  • Rate: GST is 10% of the GST-exclusive value, so the GST in a GST-inclusive amount is one-eleventh of it. ATO: How GST works, read 20 September 2026; A New Tax System (Goods and Services Tax) Act 1999.
  • Applied to your figure as a GST-exclusive amount: GST = amount / 10, rounded once to cents.Applied to your figure as a GST-inclusive amount: GST = amount / 11, rounded once to cents.
  • Supplied by you: the amount, whether it includes GST and that the supply is wholly taxable. Mixed, GST-free and input-taxed supplies are not classified here.

How it works

For a wholly taxable amount at 10% GST, exclusive amount / 10 gives GST; inclusive amount / 11 gives its GST component. Each result rounds once to cents. Mixed, GST-free and input-taxed supplies need classification first.

ATO: How GST works

One of the nine business calculators. Calculations run in this browser. The calculator code does not send your inputs to a server or save them automatically. To check, disconnect from the internet once the page has loaded, then calculate.

Planning estimates in AUD. Confirm tax treatment, liability amounts and dates separately. Amounts round to the nearest cent, with exact half cents rounded up.

Written by Ryan Duguid in his own time and on his own equipment. He is a Provisional CA ANZ Member. CA ANZ has not endorsed this site or its tools.

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Ryan Duguid is not a registered tax agent or BAS agent. Nothing here is tax, legal or financial advice. Computational outputs are review aids for a qualified professional, not compliance determinations, and lodgement decisions stay with a human.

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Ryan Duguid, ABN 59 834 031 764

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