Australia GST calculator
Add GST to an exclusive price or find the GST included in a total, in AUD.
Before you calculate. Choose the GST treatment that applies to your sale. This tool covers one ordinary AUD supply, not eligibility decisions or multi-item invoices. Human tax review is pending.
Amount: up to two decimals and A$1,000,000,000,000. Manual percentage: up to six decimals and 1,000%. Non-negative inputs only; these are input caps, not legal limits.
Choose the treatment applicable to your sale to calculate. No rate is selected automatically.
- Excluding GST
- GST amount
- Including GST
For an ordinary taxable supply, GST is 10% of the exclusive value, or one-eleventh of the inclusive price. Select the treatment to see the calculation.
Reference examples at 10% · add GST
Illustrative arithmetic, not a decision that these sales are taxable.
| Input (AUD) | Excluding GST | GST | Including GST |
|---|---|---|---|
| A$100 | A$100.00 | A$10.00 | A$110.00 |
| A$110 | A$110.00 | A$11.00 | A$121.00 |
| A$22000 | A$22000.00 | A$2200.00 | A$24200.00 |
Taxable, GST-free and input-taxed sales
The selected treatment is your input, not a classification result. The GST Act distinguishes taxable supplies from GST-free and input-taxed supplies. GST-free arithmetic here adds no GST; it does not determine credit eligibility. Input-taxed and outside-scope selections return no calculation and are never silently treated as taxable sales at 0%.
For the legal conditions, see GST Act sections 9-5 and 9-30, and Divisions 38 and 40. For the operational guidance, see ATO's official PDF, taxable/GST-free/input-taxed sections.
Calculation and rounding
One ordinary taxable supply, paid in AUD and not split into items: add GST using exclusive value × 10 ÷ 100. Remove GST using inclusive price ÷ 11. Round the GST amount to the nearest cent, with half a cent rounded up, then reconcile the other amount. Manual mode applies the entered percentage as illustrative arithmetic, not an Australian statutory rate.
The independent example in GST Act section 9-75 uses an ordinary taxable price of A$22,000, an exclusive value of A$20,000 and GST of A$2,000. This engine is tested against that example. Synthetic boundary example: A$0.05 excluding GST at 10% gives A$0.005 before rounding, shown as A$0.01 GST and A$0.06 total.
GST Act section 9-90 distinguishes one supply from several supplies and supplies divided into items. This calculator does not implement multi-item invoice rounding, cash-payment rounding, mixed supplies or GST-credit/BAS calculations. The generic calculator and formula tool have a different reverse-rounding convention; do not interchange policies at boundary cases.
ATO official PDF: rounding on page 31Scope and source dates
No eligibility, registration threshold, product category or historical transaction date is determined. Imports, exports, special schemes, luxury car tax, property margin schemes, refunds, discounts, split items and mixed baskets need separate treatment.
Legislative version checked: C2026C00081, compilation dated , identified by the Register's current-version page on 2026-10-14. This compilation date is not asserted as the GST rate's effective start. No historic/future rate lookup is provided.
Understanding your result
The worked examples use the same method as your calculation: exclusive and inclusive prices, the one-eleventh fraction and single-supply rounding.
Official sources
Latest source check: . The Federal Register provides readable legislation. The ATO PDFs below were previously reviewed, but the latest requests returned HTTP 403; full access to the ATO HTML guidance was also unavailable. These access limits do not establish whether a treatment applies to your sale.
- ATO GST guide (official PDF): rate, sales and rounding Previously reviewed PDF, pages 3, 11, 22, 31. Unavailable at the latest check (HTTP 403).
- ATO GST sales guidance (official PDF): classifications and mixed sales Previously reviewed PDF, pages 30, 41. Unavailable at the latest check (HTTP 403).
- GST Act 1999, compilation 96: sections 9-5, 9-30, 9-70, 9-75 and 9-90 Official legislation. Check transaction-specific conditions and exceptions.
- Federal Register: current GST Act version Official legislation. Check transaction-specific conditions and exceptions.
- ATO How GST works (HTML retrieval incomplete) Full page could not be verified.