GST Calculator Australia
Add or remove 10% GST from any amount. Useful for invoices, BAS prep, quoting, and decoding "$X plus GST" vs "$X including GST" so you always know what number to put where.
Last updated: · figures current for the 2025–26 financial year.
$
Ex GST
$100.00
GST (10%)
$10.00
Inc GST
$110.00
Australian GST rate: 10% (unchanged since introduction in 2000). To remove GST from a GST-inclusive amount, divide by 11 to get the GST portion. To add GST to a GST-exclusive amount, multiply by 0.10.
Quick reference: common GST calculations
| Ex GST | + GST (10%) | Inc GST |
|---|---|---|
| $100 | $10 | $110 |
| $250 | $25 | $275 |
| $500 | $50 | $550 |
| $1,000 | $100 | $1,100 |
| $2,500 | $250 | $2,750 |
| $5,000 | $500 | $5,500 |
| $10,000 | $1,000 | $11,000 |
The two formulas you actually need
Adding GST
If a price is GST-exclusive and you need the GST-inclusive total:
Inc GST = Ex GST × 1.1
Removing GST
If a price is GST-inclusive and you need to know the GST portion:
GST = Inc GST ÷ 11
Or, the ex-GST amount: Ex GST = Inc GST ÷ 1.1
Common mistake: subtracting 10% from the inc-GST price doesn't give the right answer. $110 minus 10% = $99, not $100. Always divide by 11 (for the GST) or 1.1 (for the ex-GST amount).
Worked example: a tradie quoting a $2,400 job
Jordan is a GST-registered electrician quoting a $2,400 job. The $2,400 covers his labour and materials before tax, so it's the GST-exclusive amount. To invoice correctly:
- GST to add: $2,400 × 10% = $240
- Total on the tax invoice: $2,400 + $240 = $2,640 inc GST
When the client pays $2,640, Jordan keeps $2,400 and sets the $240 aside for the ATO — it was never his money. At BAS time he reports $240 of GST collected, then subtracts the GST he paid on business purchases (say $90 of GST on cable and fittings), so he remits the net $150.
If the client had instead said "I've only got $2,640 all up", that figure is GST-inclusive. Jordan works backwards: $2,640 ÷ 11 = $240 GST, leaving $2,400 for the work. Note he does not subtract 10% from $2,640 (which would wrongly give $2,376) — inclusive amounts are always divided by 11.
When do you need a GST calculator?
- Invoicing: showing GST as a separate line item is mandatory on tax invoices over $82.50
- Quoting: clarify whether prices are inc-GST or ex-GST to avoid disputes
- BAS lodgement: separating GST collected from GST paid on business expenses
- Sole trader pricing: working out what to charge so your "after GST" income meets your target
- Reading receipts: figuring out the GST component for expense claims
What to do next
Getting the GST maths right is step one. Here's how to make sure it flows through to compliant invoices and a clean BAS.
-
Put GST as a separate line on every tax invoice
For any sale of $82.50 (inc GST) or more to a GST-registered buyer, a valid tax invoice must show your ABN, the words "Tax invoice", and the GST amount as a separate line. Without it, your customer can't claim the GST credit.
-
Set the GST aside the moment you're paid
The GST portion isn't your income — it's money you're collecting for the ATO. Many sole traders move it into a separate account on every payment so the BAS bill never comes as a surprise.
-
Track the GST you pay on business purchases
You offset GST credits on business expenses against the GST you collected. Keep tax invoices for purchases so you only remit the net amount — and get a refund if your credits exceed your collections.
-
Check whether you actually need to be registered
Registration is compulsory once your turnover hits $75,000 a year (or for any taxi/ride-share income). Below that it's optional — worth it if most of your customers are GST-registered businesses who can claim it back.
Frequently asked questions
What is the GST rate in Australia?
Australia's GST (Goods and Services Tax) rate is 10%, and it has been since GST was introduced on 1 July 2000.
Unlike sales taxes in some countries, GST is a broad-based consumption tax — it applies to most goods and services, with specific exemptions for essentials like fresh food, education, health services, and some financial services.
How do I remove GST from a price?
To remove GST from a GST-inclusive amount, divide by 11. The result is the GST portion. The original amount minus that gives you the ex-GST price.
Example: $110 inc-GST → GST is $110 ÷ 11 = $10 → ex-GST is $100.
Common mistake: people divide by 1.1 expecting to remove 10%, which gives the ex-GST price, but they sometimes confuse this with "subtract 10%" which gives the wrong answer.
How do I add GST to a price?
To add GST to a GST-exclusive amount, multiply by 1.1 (or add 10%).
Example: $100 ex-GST × 1.1 = $110 inc-GST.
The GST itself is the difference: $110 − $100 = $10.
When do I need to register for GST?
You must register for GST if your business has GST turnover of $75,000 or more per year (or $150,000+ for non-profits, or any amount if you provide taxi/ride-share services).
You can also register voluntarily if you're under the threshold — useful when most of your customers are GST-registered businesses (they can claim the GST back, so it doesn't cost them anything; meanwhile you can claim GST credits on your own purchases).
Once registered, you charge GST on taxable supplies, lodge a Business Activity Statement (BAS) regularly (monthly, quarterly, or annually depending on turnover), and remit the net GST to the ATO.
What's GST-free vs input-taxed?
Both are exemptions from GST, but they work differently:
- GST-free: you don't charge GST on the supply, but you can still claim GST credits on related business purchases. Examples: most basic food, education, exports, medical services.
- Input-taxed: you don't charge GST on the supply, AND you cannot claim GST credits on related purchases. Examples: residential rent, financial services (banking, insurance), most second-hand goods.
Most businesses dealing in input-taxed supplies should consult an accountant — the rules around partial input taxation are complex.
Can I claim GST back on business purchases?
Yes — if you're GST-registered, you can claim "GST credits" (also called input tax credits) on most purchases used in running your business.
To claim GST credits, you need:
- A valid tax invoice from your supplier
- The purchase to be a genuine business expense (not personal use)
- The supply to have included GST
You report and offset GST credits against the GST you collected from customers when lodging your BAS. If credits exceed collections, the ATO refunds the difference.
Does GST apply to overseas online purchases?
Yes, since 2018. The "low-value imported goods" rules require overseas businesses selling more than $75,000/year to Australian consumers to register for GST and charge it.
So your $20 t-shirt from a US retailer should include GST, just like a local purchase. For high-value imports (over $1,000), GST is collected at the border by Australian Border Force / customs.
Digital services (Netflix, Spotify, software subscriptions) from overseas providers also charge GST under the "Netflix tax" rules.
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