How to calculate GST in Australia
Australia's Goods and Services Tax (GST) is a flat 10% on most goods and services. The maths is simple once you know which direction you're going — this calculator does both, but here's what's happening under the hood.
Adding GST to a price
If you have a price that excludes GST and want the GST-inclusive total, multiply by 1.1:
- GST amount = price × 10% (e.g. $200 × 0.10 = $20)
- Total including GST = price × 1.1 (e.g. $200 × 1.1 = $220)
Removing GST from a total
If you have a GST-inclusive total and want to find the GST portion, divide by 11 — not by 10. This trips a lot of people up:
- GST included = total ÷ 11 (e.g. $220 ÷ 11 = $20)
- Price before GST = total ÷ 1.1 (e.g. $220 ÷ 1.1 = $200)
Why one-eleventh? Because the 10% was added to the smaller pre-GST figure, so GST is 1/11th of the grossed-up total, not 1/10th.
Need to put the result on a tax invoice? The Australian tax invoice generator calculates inclusive or exclusive GST and exports a PDF. Check the GST treatment and finished invoice before sending.
Do you need to charge GST?
For most businesses, GST registration is required when current or projected annual GST turnover reaches $75,000. Taxi and ride-sourcing drivers must register regardless of turnover. Registration can also be voluntary. If registered, charge GST on taxable sales; some supplies are GST-free or input-taxed. If not registered, do not charge GST. Read the ATO registration rules, our threshold guide and tax invoice guide.
Frequently asked questions
How do I calculate GST in Australia?
To add GST, multiply the price by 1.1. To find the GST inside a GST-inclusive total, divide the total by 11. To get the price before GST, divide the total by 1.1.
How do I remove GST from a total?
Divide the GST-inclusive amount by 11 to get the GST portion, then subtract it from the total for the GST-exclusive price. $110 includes $10 GST and $100 before GST.
What is the GST rate in Australia?
10%, applied to most goods and services. Some items are GST-free, such as basic food and certain health and education services.
Do I need to charge GST?
Only once your GST turnover reaches $75,000 a year (or from day one for taxi and ride-share drivers). Below that, registration is optional.
General information, not tax advice — check the ATO for your situation.