Australian GST calculator
Australian GST calculator at the 10% rate in force since 1 July 2000: convert GST-inclusive to GST-exclusive and back, see how GST-free supplies differ from input-taxed ones, and round the GST down to the cent the way the ATO allows.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Amount and method
All amounts are computed in integer cents. GST is 10%, in force since 1 July 2000; the rate table holds editable reference values.
Rate table (editable)
Editing a rate recalculates immediately; the effective date column shows when that band started.
| Scope | Rate (%) | Effective from | GST exclusive | GST | GST inclusive | GST share of gross |
|---|---|---|---|---|---|---|
| Taxable supplies: most goods and services (standard 10% rate) | 2000-07-01 | 100.00 | 10.00 | 110.00 | 9.09% | |
| GST-free: most basic food, medical services, education, exports | 2000-07-01 | 100.00 | 0.00 | 100.00 | 0.00% | |
| Input-taxed: financial services, residential rent, some residential sales | 2000-07-01 | 100.00 | 0.00 | 100.00 | 0.00% |
What this tool does
- Quote an Australian customer a GST-inclusive price from a GST-exclusive cost.
- Take a GST-inclusive invoice apart into the net amount and the GST you can claim.
- Check the GST figures on a BAS to confirm they follow the one-eleventh rule.
- Decide whether a supply is taxable, GST-free or input-taxed using the scope notes in the rate table.
Example
Input
Amount 100 AUD, direction “GST exclusive → inclusive”, rounding “Round to the nearest cent”
Output
Standard rate row: GST exclusive 100.00, GST 10.00, GST inclusive 110.00, GST share of gross 9.09%
Switch the direction to “GST inclusive → exclusive” and enter 110: the standard row recovers 100.00 exclusive and 10.00 GST.
Frequently asked questions
What is the Australian GST rate and when did it start?
The standard rate is 10%, in force since 1 July 2000 and unchanged since. Changing it requires legislation, which is why the effective date sits in the rate table so you can check older documents.
Why is the GST in a GST-inclusive price one eleventh?
Because the inclusive price is the exclusive price × 1.1, so the exclusive price is inclusive ÷ 1.1 and the GST is inclusive × 10/110 = inclusive ÷ 11. On 110 AUD inclusive, the GST is 10 AUD and the net is 100 AUD.
What is the difference between rounding down and rounding to the nearest cent?
The ATO allows you to round the GST payable on each taxable supply down to the nearest cent. On 109 AUD inclusive, rounding gives 10.00 GST and 99.00 net, while rounding down gives 9.00 GST and 100.00 net. Over many invoices the two conventions drift apart.
GST-free and input-taxed are both 0% — why list them separately?
They are treated differently: GST-free supplies normally let you claim input tax credits, while input-taxed supplies such as financial services and residential rent generally do not. The right category depends on the supply itself, so confirm the classification with your tax adviser.
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