Updated 8 November 2026

The calculators on GSTCal apply the standard GST formulas to the amount you enter. They don’t know what you’re buying or selling, so they can’t tell whether a sale is taxable, GST-free or input-taxed, or whether you’re registered for GST.

Our calculators and guides are general information. They don’t take your personal circumstances, objectives or financial situation into account, and they are not financial, legal or tax advice. Before you rely on a figure for a tax return, a business activity statement (BAS) or an invoice, check it with the Australian Taxation Office (ATO) or a registered tax agent.

Results are rounded to the nearest cent, with half a cent rounded up. Accounting software that rounds GST on an invoice total instead of each line may differ by a cent or two. Both methods can be acceptable to the ATO.

The calculator defaults to Australia’s 10% GST rate. If you change the rate, the result is a simple percentage calculation and doesn’t reflect any other country’s tax rules.

GSTCal is independent. We are not affiliated with, endorsed by or acting for the ATO or any other Australian government agency.

Tax rules can change. If you find an error, please contact us.