Formula
Add GST: GST = amount x 10%, total = amount x 1.10. Remove GST: GST = amount - amount / 1.10, exclusive amount = amount / 1.10.
GST Calculator
Add or remove Australian 10% GST from a price and show the exclusive amount, GST component and inclusive total.
Worked example
Adding GST to $100 gives $10 GST and a $110 total. Removing GST from $110 gives $10 GST and $100 before GST.
Professional note
Professional note: print the input values, formula, result and date together so the calculation can be reviewed later.
Regional and unit assumptions
Basis: Australian GST at 10%. Some supplies are GST-free or input taxed, so confirm treatment with ATO guidance or an adviser.
GST proof
Add or extract 10 percent GST
GST-inclusive and GST-exclusive prices use different arithmetic. The page states whether it is adding GST to a net amount or extracting the GST component from an inclusive amount.
Visible checks
What the page now proves
- Exclusive amount
- GST component
- Inclusive total
Assumptions and limitations
- This calculator is for planning and education, not legal, tax, medical, immigration, engineering or financial advice.
- Use current official rates, contracts, carrier terms, statutes or professional guidance before relying on the result.
- The default values are examples. Replace them with the figures from the job, invoice, contract, bill, service or record being checked.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Add GST: GST = amount x 10%, total = amount x 1.10. Remove GST: GST = amount - amount / 1.10, exclusive amount = amount / 1.10.
Standard or basis
Basis: Australian GST at 10%. Some supplies are GST-free or input taxed, so confirm treatment with ATO guidance or an adviser.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Professional note: print the input values, formula, result and date together so the calculation can be reviewed later.
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Questions
What is the GST Calculator?
The GST calculator adds 10% GST to an Australian price or extracts the GST component from a GST-inclusive price.
Can I rely on this as professional advice?
No. Use it as a transparent planning estimate, then verify the current rule, rate, contract or official source for the decision you are making.