How GST is calculated
Rates checked 15 Oct 2026 against the ATO's GST guide.
Australia's GST rate is 10%.
- Add GST: price × 1.1. $100 + GST = $110.
- Remove GST: price ÷ 1.1. $110 includes $10 GST.
- GST in a GST-inclusive price: price ÷ 11. For $220, GST is $20.
A common mistake is taking 10% off a GST-inclusive price: $110 − 10% = $99, not $100.
Adding GST
| Price before GST | GST | Total |
|---|---|---|
| $50 | $5.00 | $55.00 |
| $99 | $9.90 | $108.90 |
| $1,000 | $100.00 | $1,100.00 |
| $5,500 | $550.00 | $6,050.00 |
Removing GST from a total
| Total with GST | GST inside | Price before GST |
|---|---|---|
| $50 | $4.55 | $45.45 |
| $99 | $9.00 | $90.00 |
| $1,000 | $90.91 | $909.09 |
| $5,500 | $500.00 | $5,000.00 |
General information only, not financial, tax or credit advice. Check your situation with the ATO, your state revenue office or a licensed adviser.
GST FAQs
How do I calculate GST from a total?
Divide the total by 11. For a $1,000 GST-inclusive price, the GST is $1,000 ÷ 11 = $90.91, and the price before GST is $1,000 ÷ 1.1 = $909.09.
How much GST is in $100?
$9.09. A $100 GST-inclusive price is $90.91 before GST. Taking 10% off would give $90, which is wrong.
What is $1,000 plus GST?
$1,100: $1,000 × 1.1, of which $100 is GST.
Is GST charged on fresh food, rent or medical?
Mostly no. The ATO lists most basic food, some medical, health and care services, some medicines and some medical aids as GST-free. Renting out a home is input taxed, so residential rent has no GST. Not every food is GST-free, so check the ATO's detailed food list.
Why divide by 11?
Because a GST-inclusive price is 110% of the base price, GST is 10/110 = 1/11 of the total.
Do I need to charge GST?
Generally, businesses must register for GST when their GST turnover is $75,000 or more. Check the ATO's GST guide for your situation.