GST calculator
Add GST to a price or pull it out of a total. Use one line or a full invoice – the totals update as you type.
You've changed the rate from 10%. Australian GST is 10% – other rates are only useful for what-ifs or NZ GST (15%).
Rate checked 3 Nov 2026: 10%. Source: ATO – GST.
How it works
GST = price × 0.1 and total = price × 1.1GST = total ÷ 11 and price excl. GST = total ÷ 1.1With a custom rate r, removing GST is GST = total × r ÷ (1 + r).
Worked example
A plumber quotes $480 plus GST. The GST is $480 × 0.1 = $48, so you'll pay $528.
Going the other way, a receipt shows $82.50 including GST. The GST is $82.50 ÷ 11 = $7.50, and the price before GST was $75.00.
For an invoice with 3 hours' labour at $95 and $140 of parts (both before GST), the subtotal is $425, GST is $42.50 and the total is $467.50.
Common questions
What is the GST rate in Australia?
GST is 10% on most goods and services sold in Australia. Some things are GST-free, such as most basic food, many health and medical services, and some education courses.
How do I work out GST from a total price?
Divide the GST-inclusive price by 11. For example, $110 ÷ 11 = $10 GST, so the price before GST was $100.
How do I add GST to a price?
Multiply the price by 1.1. A $250 price becomes $275 including GST, with $25 of that being GST.
Why not just take 10% off the total?
Because the 10% applies to the pre-GST price, not the total. Taking 10% off $110 gives $99, which is wrong – the right answer is $100.
Can I work out GST for a whole invoice?
Yes. Add a line for each item, set the quantity, and the calculator totals the GST for you. On a real tax invoice, rounding is usually done on the total, which is what this does too.
Why would I change the rate?
Australian GST is 10%, so most people never need to. It's there for what-ifs, or for New Zealand GST, which is 15%.
Do I have to charge GST?
Generally only if your business is registered for GST. You must register once your GST turnover hits $75,000 a year ($150,000 for non-profits), and taxi and ride-share drivers must register regardless. The ATO has the details.