How to calculate GST in Australia
GST is a flat 10%, so the maths is simple once you know two tricks: how to add it to a price, and how to pull it out of a total.
Goods and Services Tax in Australia is a flat 10% on most things you buy and sell. Whether you are pricing a job or checking an invoice, there are just two calculations to know.
Adding GST to a price
If you have a price before GST, multiply it by 1.1 to get the GST-inclusive total, or by 0.1 to get the GST alone. So a $1,000 service becomes $1,100, of which $100 is GST.
Removing GST from a total
This is where people slip up. To find the GST inside a GST-inclusive price, you do not take 10% — you divide by 11. On a $1,100 total, the GST is $1,100 ÷ 11 = $100, and the price before GST is $1,000. (Dividing the total by 1.1 gives the same ex-GST figure.)
Worked example
Chloe runs a small design studio and quotes $3,000 for a project. Adding GST, she invoices $3,300. When her client pays, Chloe sets aside the $300 of GST to send to the ATO on her next BAS — it was never her money to keep.
When you have to register
You must register for GST once your business turnover hits $75,000 a year ($150,000 for non-profits), or immediately for taxis and rideshare. Once registered, you charge GST on sales, claim back the GST on your purchases, and report the difference on your Business Activity Statement, usually quarterly. Some things are GST-free, including most basic food, and many health and education services.
Calculate GST instantly
Add or remove 10% GST on any amount and see the full breakdown.
This is general information, not personal advice. If you run a business, see our sole trader vs company guide.
Frequently asked questions
How do I calculate GST in Australia?
To add GST, multiply the price by 1.1 for the total (or by 0.1 for the GST alone). To find the GST inside a GST-inclusive total, divide by 11 — GST is one-eleventh of the total, not one-tenth.
How do I remove GST from a price?
Divide the GST-inclusive amount by 11 to get the GST, or divide by 1.1 to get the price before GST. For example, $1,100 has $100 of GST and a $1,000 ex-GST price.
When do I need to register for GST?
Once your business turnover reaches $75,000 a year ($150,000 for non-profits), or straight away for taxi and rideshare drivers. Below that, registration is optional but lets you claim GST credits.
Is everything subject to GST?
No. Most goods and services include 10% GST, but some are GST-free — including most basic food, many health and education services, and exports.