GST calculator: add GST or take it out
GST is 10%, and the GST inside a price that includes it is one-eleventh of that price. So $220 including GST is $200 plus $20 GST.
The calculators
Add GST to a price
Enter a price before GST to see the GST and the total.
Take GST out of a price
Enter a price that includes GST to see how much of it is GST.
Both calculators work in whole cents, so the answers are exact. Where the GST is not a whole number of cents, it is rounded to the nearest cent, with half a cent rounded up. If your accounting software rounds differently, a total can differ by a cent.
Adding GST and taking it out.
GST is 10%. To add GST to a price, add a tenth of the price: $200 plus $20 GST is $220.
To take GST out of a price that already includes it, do not take 10% of the total. The total is the price plus a tenth of the price, which is 110% of the price, so the GST in it is one-eleventh of the total. One-eleventh of $220 is $20, which leaves $200.
Good to know.
How do I add GST to a price?
Add a tenth of the price. For a $200 price, the GST is $20 and the total is $220. The calculator above does the sum to the cent.
How do I take GST out of a price that includes it?
Divide the GST-inclusive price by 11 to get the GST, then take that off the price. $220 including GST is $20 of GST and $200 before GST. Taking 10% off the total ($22 here) gives the wrong answer.
When do I have to register for GST?
In general, when your GST turnover (your gross business income minus GST) reaches $75,000, or $150,000 for non-profit organisations. Once you are required to register you have 21 days to do it. Below the threshold registering is optional, and if you choose to register you generally stay registered for at least 12 months. You need an ABN before you can register. If you do not register when you are required to, you may have to pay GST on the sales made since the date you were required to register, even if you did not include GST in the price. The ATO page has the full rules, and your accountant can tell you where you stand.
Which way does this calculator round?
To the nearest cent, with half a cent rounded up. For example, the GST on $0.05 is half a cent, which rounds up to 1 cent. If your accounting software rounds differently, a total can differ by a cent.
Where the numbers come from.
Checked against the ATO pages on 24 October 2026.
- ATO: How GST works (page updated 14 September 2026)
- ATO: Registering for GST (page updated 14 September 2026)
Kept's tax tools are estimates to help with your reporting, not professional advice: check anything that matters with your accountant.
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