Australian GST estimate
Use this calculator when you have a GST-exclusive amount and want to estimate GST and the GST-inclusive total. The default 10% reflects the general GST rate for taxable sales, but the tool does not decide whether a sale is taxable, GST-free or input-taxed.
Exclusive and inclusive prices
For a taxable sale, GST on a $150 exclusive amount is $15, giving a $165 total. If $165 is already GST-inclusive, adding another 10% would double-count GST. At the general 10% rate, the GST component of a fully taxable inclusive price is commonly found by dividing the total by 11.
Mixed supplies, adjustments, credits, rounding, and business activity statement reporting are outside this calculator. A receipt or tax invoice may also include items with different GST treatments.
Before using the result
Confirm whether the amount entered excludes GST, whether the supplier is charging GST, and whether every item uses the same treatment. For a real transaction, use the tax invoice and current Australian Taxation Office guidance.
Australian Taxation Office: GST guidance
Frequently asked questions
Does the calculator remove GST from an inclusive price?
No. Its main calculation adds the entered rate to an exclusive amount. Use the inclusive-price method only when the sale is fully taxable at the rate you are checking.
Are GST-free and input-taxed sales the same?
No. They have different business consequences even though GST may not appear in the customer price.
Can I use this for a BAS?
No. It does not account for tax credits, adjustments or reporting periods.