Calculator comparison
GST Inclusive vs GST Exclusive
For an ordinary taxable Australian sale, add 10% to the ex-GST amount or divide the inclusive total by 1.1. The GST already inside a total is one-eleventh.
Updated 16 October 2026 • Tools by Layna Editorial Team • General information
The percentage base is different
GST-exclusive means the price before GST. GST-inclusive means the total including it. For an ordinary fully taxable Australian sale at 10%, GST is 10% of the exclusive amount, but one-eleventh of the inclusive amount.
Those are the same tax amount calculated from different starting values. Subtracting 10% from an inclusive price does not remove GST correctly.
Use the formula for your starting amount
| What you know | Formula | Example |
|---|---|---|
| Exclusive amount E | GST = E × 0.10 | 100 × 0.10 = $10 |
| Exclusive amount E | Inclusive = E × 1.10 | 100 × 1.10 = $110 |
| Inclusive total I | GST = I ÷ 11 | 110 ÷ 11 = $10 |
| Inclusive total I | Exclusive = I ÷ 1.10 | 110 ÷ 1.10 = $100 |
Worked example: a $275 inclusive invoice
For a hypothetical fully taxable total of $275 including GST, GST is 275 ÷ 11 = $25. The exclusive amount is 275 − 25 = $250. Check: $250 × 10% = $25, then $250 + $25 = $275.
Taking 10% off $275 would remove $27.50 and leave $247.50. That is a 10% price discount, not the correct removal of the GST contained in the total.
Check whether the ordinary example applies
The arithmetic above assumes the whole sale is taxable at the standard rate. GST-free, input-taxed and mixed supplies need their actual tax treatment; you cannot assume every invoice total contains one-eleventh GST. A calculator does not decide registration obligations or whether a sale is taxable.
When comparing costs and selling prices, label the basis and use it consistently. Recoverable GST, non-recoverable GST and business expenses can affect accounting treatment. The ATO’s guidance and your accountant should determine the treatment rather than a generic percentage tool.
Use the relevant calculator
Frequently asked questions
Why divide an inclusive total by 11?
An exclusive price of $10 plus $1 GST totals $11. The GST is therefore one of the eleven equal parts in that total.
Can I remove GST by subtracting 10%?
No. For a fully taxable inclusive amount, divide by 1.1 to find the exclusive amount or divide by 11 to find the GST.
Does every sale include GST?
No. The tax treatment depends on the sale and the seller’s circumstances. Do not infer it from the existence of a price.
Sources and method
The worked figures are illustrative arithmetic. The references below explain the underlying definitions and limits.