Australian GST Calculator (10%)
Australia's GST is blessedly simple, a flat 10%, yet it sparks endless invoice arguments, because the tax hides inside the total. This free Australian GST calculator for the 10 percent rate adds GST to a price or pulls it back out of a GST inclusive total, showing the ex GST amount and the GST slice side by side. Built for invoices, quotes, BAS prep and receipt checking, with a custom rate mode for the odd case. Covers both directions, adding 10 percent GST to a net price and extracting it from a GST inclusive total, the same maths the ATO uses on your BAS.
Last updated: October 22, 2026
Your result
GST is 10% on most supplies.
The formula
Add GST: GST = price × 10%, and GST inclusive price = price × 1.1Remove GST: ex GST price = GST inclusive price ÷ 1.1GST component of an inclusive price = inclusive price ÷ 11
A worked example
Adding GST to a $500.00 quote gives $50.00 of GST and a total of $550.00. Working backwards from a $1,100.00 GST inclusive invoice, the ex GST price is $1,000.00 and the GST component is $100.00, which is one eleventh of the total.
More about the GST Calculator (Australia)
Australia's flat 10% GST
Two examples cover 90% of real life. Adding: a $500 ex GST quote, multiply by 1.1, the GST is $50.00 and $550.00 is the number on the invoice. Removing: a $1,100 GST inclusive invoice, divide by 1.1 for the $1,000.00 ex GST price, and the GST component is $100.00 (check it with the divide by 11 trick: $1,100 ÷ 11 = $100). Three figures, no ambiguity, BAS ready.
The classic GST moments: writing your first proper tax invoice and realising all three figures have to be on it; checking a supplier's invoice before you claim the credit; preparing a BAS and splitting GST paid from GST collected; quoting a job and deciding whether your price is ex- or inc GST (state it explicitly, disputes over this never end). The custom rate mode also covers the rare non 10% cases and GST free supplies you need to show separately.
For businesses: BAS and good records
A few bookkeeper habits worth stealing. Always label quotes and invoices ex GST or inc GST, unlabelled figures cause most GST arguments. Round per line item, not just at the total. Keep the ex GST, GST and total together in your records: the ATO wants to see the split, and reconstructing it months later from totals alone is miserable. And watch the registration threshold ($75,000 turnover): cross it and GST stops being optional.
One limit to respect: this is arithmetic, not tax advice. It cannot decide whether a supply is taxable, GST free or input taxed, basic foods, many health services and education each have their own rules, and misclassifying dwarfs any rounding error. For classification questions the ATO's guides (or your accountant) are the authority. The rates and thresholds reflect current published figures; budgets can move them.
Worked example: pulling the GST out of a $550 charge
A supplier invoices you $550, GST included, and you need the tax figure for your records. Because the 10 percent was added to a $500 base, the GST is exactly one eleventh of the total: 550 ÷ 11 = $50. The ex GST amount is $500 and the GST component is $50. Run the same division on any inclusive figure, $1,100 contains $100 of GST, $220 contains $20.
The check that catches most errors: the ex GST amount plus the GST must rebuild the total exactly. If your split of $550 gives you $505 and $45, the addition still totals $550, but 505 × 1.1 = $555.50, which exposes the wrong split instantly. Always verify by re adding 10 percent to the base, not just by adding the two pieces.
Quoting ex GST without undercharging yourself
Suppose your service is priced at $275 plus GST. The GST is 275 × 0.10 = $27.50, so the client pays $302.50 in total. The expensive mistake is working backwards from a round number you promised, agreeing to “$300 all up” and then discovering the GST inside it is 300 ÷ 11 = $27.27, leaving you $272.73 for a job you priced at $275.
So decide, before any quote leaves your desk, whether your prices are quoted inclusive or exclusive, and write the words “plus GST” wherever they apply. Most invoice disputes about tax are really disputes about which of those two understandings the client walked away with. The calculator removes the arithmetic argument; only clear wording removes the expectations argument.
Small GST habits that make BAS time boring
Record the GST component at the moment you raise or pay an invoice, not from memory at BAS time. A shoebox of receipts forces you to re derive every figure under deadline pressure, and the divide by eleven work you skipped in March becomes an evening of it in April. Two extra columns in your bookkeeping, GST charged, GST paid, turn the quarterly return into copying, not archaeology.
Keep personal and business spending visibly separate, because mixed purchases are where GST claims go wrong: claiming the tax on a whole receipt when only part of it was a business expense inflates the claim, while binning mixed receipts entirely throws away credit you were entitled to. Split the receipt at the till where you can, and note the business share on it where you cannot.
How to use the GST Calculator (Australia)
- Choose whether to add GST to a price or remove it from a GST inclusive total.
- Enter the amount in Australian dollars.
- Leave the rate at 10%, or pick GST free or a custom rate.
- Press Calculate and copy the ex GST price, GST amount and total.
Frequently asked questions
Why is the GST one eleventh of the total instead of ten percent?
Because the total already contains the tax, picture 11 equal parts: 10 parts ex GST price, 1 part GST. On a $110 total the GST is $10, which is 10/110, or one eleventh. Ten percent of the ex GST price and one eleventh of the inclusive price are the same dollars; the mix up is always about which number you start from.
When does my business have to register for GST?
Once your GST turnover hits $75,000 a year ($150,000 for non profits). Taxi and rideshare drivers must register whatever their turnover. Under the threshold it is your choice, but voluntary registration lets you claim GST credits on business purchases, which is why plenty of small businesses sign up early. The ATO is the final word on current thresholds; they do change.
Is GST already in the price on the shelf?
Yes, advertised retail prices must include GST by law, so the ticket price is the price you pay. The confusion starts with invoices and quotes, where businesses often quote ex GST. Flip to the remove GST mode above whenever you need to pull the tax back out for your books.
How should GST rounding work on a multi line invoice?
Round the GST on each line item to the nearest cent. That matches the ATO's expectation and is the safest habit. Rounding once on the final total can leave your invoice a few cents adrift of the buyer's records, and that is exactly the reconciliation headache nobody has time for.
What is the difference between GST free and input taxed?
GST free supplies (fresh food, exports, medical services, education) carry 0% GST and the seller can still claim GST credits on business inputs. Input taxed supplies (financial services, residential rent, charity fundraising) have no GST charged, and the seller cannot claim credits either, so the GST paid on costs simply becomes a business expense.
Can I claim GST back on business expenses?
If you are registered, yes. The GST you pay on creditable business purchases is claimed as GST credits on your BAS and offset against the GST you collected on sales. You remit only the difference to the ATO. Keep tax invoices for any purchase over $82.50 including GST; without them the ATO can deny the credit.
Do I charge GST on exports from Australia?
Generally no, exports of goods are GST free, so you do not add 10% for overseas buyers. You can still claim GST credits on the business inputs used to produce the exported goods. Keep records proving the goods actually left Australia, since the ATO can ask for evidence. Run any borderline case past your accountant, because the paperwork matters as much as the rate here.
What is the GST rate in Australia for 2026-27?
Australia's Goods and Services Tax remains 10% on most goods and services in 2026-27. Businesses must register for GST once their annual turnover reaches $75,000 ($150,000 for non profit organisations).
How do I remove 10% GST from a price in Australia?
Divide the GST inclusive price by 11 to get the GST component, or by 1.1 to get the GST exclusive price. For example, $110 including GST contains $10 GST and is $100 excluding GST. To add GST, multiply the exclusive price by 1.1.
What does it mean when a quote says plus GST?
It means the figure quoted is the pre tax price, and 10 percent will be added on the invoice. A quote of $800 plus GST becomes an invoice total of $880, with $80 of GST shown separately. The words matter enormously in disputes: a price quoted with no mention of GST is generally treated by the customer as the full amount payable, whatever the seller intended, so write the basis on every quote.