Australian GST Calculator: Add or Remove 10% GST
Work out the GST-exclusive price, GST amount and total for an ordinary taxable sale in Australia. Choose whether your starting figure already includes GST.
An example is loaded. Replace it with your figures. All amounts are AUD.
- Excluding GST
- $100.00
- GST (10%)
- $10.00
- Including GST
- $110.00
GST = GST-exclusive amount × 10%. Add that GST to find the total price.
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How to calculate Australian GST
To add GST, multiply a GST-exclusive price by 0.10, then add the result to your price. A $100 taxable sale has $10 GST and a $110 total. Multiplying the original price by 1.10 gives the same total.
To extract GST from an inclusive total, divide by 11. A $220 GST-inclusive invoice contains $20 GST and a $200 underlying price. Taking 10% off $220 would subtract $22, which is the wrong calculation.
When this calculator applies
This tool assumes the whole amount is subject to ordinary 10% GST. A price alone cannot establish whether GST applies. GST-free sales, input-taxed supplies, mixed supplies and special rules such as the property margin scheme need different treatment.
Do not add GST merely because you have an ABN. Check your registration obligations and the type of supply. A GST component on an expense also does not, by itself, establish that you can claim a GST credit.
Rounding and invoices
Results are rounded to cents. The exclusive amount and GST reconcile to the displayed inclusive total. Calculating invoice lines separately can produce a small rounding difference from calculating GST on one total; use the ATO's tax-invoice guidance and your accounting software's consistent method.
This is a price calculator, not a BAS estimator. A BAS can include GST credits, adjustments, PAYG and other obligations. Keep source invoices and reconcile your records before lodging.
Common questions
How much GST is in $1,100?
For a fully taxable GST-inclusive amount, $1,100 ÷ 11 = $100 GST. The price before GST is $1,000.
Can I remove GST by subtracting 10%?
No. Divide an inclusive price by 1.10 to get the exclusive price, or divide by 11 to find just the GST component.
Put the result to work
Sources and assumptions
Formula notes checked 5 September 2026. Examples are illustrative; these tools provide general information.