Free calculator
GST calculator
Enter a price and choose whether to add GST or take it out. You get the price before GST, the GST and the total your tax invoice will show.
GST
$100.00
- Price before GST
- $1,000.00
- GST at 10%
- $100.00
- Total including GST
- $1,100.00
How GST is worked out
GST is 10% of the price before GST. On $1,000 the GST is $100 and the total $1,100.
To take GST out of a price that includes it, divide by 11: $1,100 includes $100 of GST. That one-eleventh rule works only when the whole price is taxable.
Round GST to the nearest cent, with half a cent rounding up. On an invoice with several taxable items you can total the GST once, which is what our invoice generator does.
When you charge GST
- Only once you’re registered for GST — compulsory at $75,000 GST turnover a year ($150,000 for non-profits), and for taxi and ride-sourcing drivers from day one.
- Not on GST-free sales such as most basic food, some health and education services and exports.
- Not on input-taxed sales such as residential rent and financial supplies.
Last updated 2026-10-01. This calculator is a guide, not tax advice.
Frequently asked questions
How do I calculate GST from a total?
Divide the GST-inclusive total by 11. $550 includes $50 of GST, so the price before GST is $500.
Do I charge GST if I’m not registered?
No. Until you register, your invoices show no GST and must not be titled “Tax Invoice”. Quote your ABN anyway.
Is GST the same in every state?
Yes. GST is a national 10% tax and Australia has no state sales taxes.