GST Calculator

How do I calculate the GST in a price?

To find the GST inside a GST-inclusive price, divide the total by 11. That works because a GST-inclusive price is 11 equal parts: 10 parts base price and 1 part GST. So a $1,100 invoice includes $100 of GST ($1,100 divided by 11). To add GST instead, multiply the GST-exclusive amount by 1.1.

Is GST always 10%?

The GST rate in Australia is 10%, and it has not changed since GST began in 2000. Not everything carries it, though: some items are GST-free, such as most basic food, and some are input-taxed. If you are unsure how GST applies to what you sell, check with the ATO or your accountant.

How the GST calculation works

To add GST, the calculator multiplies your amount by the GST rate and adds it on, so a $1,000 amount at 10% becomes $1,100 including $100 of GST. To remove GST, it works backwards from the GST inclusive figure: it divides by 1 plus the rate to find the base amount, then the GST is the difference. GST registered businesses generally include GST in their prices and report it to the ATO.