Australia GST Calculator
Add or remove 10% GST (divide by 11), work back from a GST amount, handle invoices with several lines and GST-free items using the ATO rounding rules, and estimate your BAS: GST on sales (1A), GST credits (1B) and the net amount to pay or refund.
How it works
GST = ex-GST price × 10%; from an inclusive price: GST = price ÷ 11, ex-GST = price − GST (= price ÷ 1.1); from a GST amount: ex-GST = GST × 10, inc-GST = GST × 11; mixed sales: GST applies to the taxable part only; BAS: 1A = (G1 − GST-free sales) ÷ 11, 1B = (G10 + G11 − purchases with no GST) ÷ 11, net = 1A − 1B
Australia’s GST is a flat 10% on most goods and services, so a GST-inclusive price is exactly 11 tenths of the ex-GST price. That is where the “divide by 11” rule comes from: the GST in any inclusive price is one eleventh of it. Choose Remove GST for a receipt or quote that already includes GST, Add GST to put GST on a price, or From GST amount when you only know the tax. Basic food, most health and education services, and exports are GST-free, while residential rent and most financial services are input-taxed. Enter the GST-free share of a mixed bill, or list invoice lines and mark the GST-free ones “free”. The ATO lets you round GST to the nearest cent either once on the invoice total or on each line. Both methods are available, and they can differ by a cent or two. The BAS estimate takes your sales (G1), GST-free sales, and capital (G10) and non-capital (G11) purchases. It works out GST on sales at 1A and your credits at 1B, then the net amount to pay or have refunded, in whole dollars as the BAS requires.
Worked example
A $550 invoice includes $50 of GST ($550 ÷ 11); the ex-GST price is $500. A $200 supermarket bill where $80 is GST-free basic food has $120 taxable, so the GST is $120 ÷ 11 = $10.91. For a quarter with $55,000 of sales, of which $5,000 were GST-free, 1A is $50,000 ÷ 11 = $4,545. With $22,000 of purchases, of which $2,000 had no GST, 1B is $20,000 ÷ 11 = $1,818. The BAS shows $2,727 to pay.
Sources: ATO — Tax invoices (thresholds and GST rounding) · ATO — Completing your BAS for GST · ATO — Simpler BAS GST bookkeeping guide
Frequently asked questions
How do I remove GST from a price?
Divide the GST-inclusive price by 11 to get the GST, then subtract it. $550 ÷ 11 = $50 GST, leaving $500. Dividing by 1.1 gives the same ex-GST figure. Removing 10% of the inclusive price is wrong: it would give $55.
Is GST charged on imports?
Yes — on goods over $1,000 at the border, and on low-value goods and digital services by registered overseas sellers.
Do I show prices with or without GST?
Consumer prices must be GST-inclusive; business-to-business quotes often state ex-GST plus GST.
How is GST rounded on an invoice?
Round the GST to the nearest cent, with half a cent rounded up. With several taxable items you can either work out GST on the invoice total (total invoice rule) or on each item and add them (taxable sale rule). Both are allowed, and the calculator does either.
What goes in 1A and 1B on the BAS?
1A is the GST included in your taxable sales and 1B is the GST in purchases you can claim credits for. If 1B is larger than 1A, you get a refund. Report whole dollars and keep tax invoices for purchases over $82.50.
When do I have to register for GST?
When your GST turnover reaches $75,000 a year ($150,000 for non-profit organisations). Taxi and ride-sourcing drivers must register whatever their turnover. Below the threshold registration is optional.
Related calculators
Uses 2025–26 Australian rates and thresholds (residents). Figures change each July — confirm with the ATO, your state revenue office or a registered tax agent. Educational estimate, not tax advice.