Australia’s Goods and Services Tax is a flat 10% applied to most goods and services — and whether you’re writing a quote, reconciling invoices, or preparing your quarterly BAS, you’ll need to add or remove GST quickly and accurately.
This free Australian GST calculator does both instantly: add GST to an ex-GST price to get the customer-facing total, or extract the GST component from a GST-inclusive amount to find the net price and GST portion. It also handles bulk calculations for multiple units or invoices in one step.
It’s built for Australian small business owners, freelancers, contractors, and bookkeepers who need a fast, reliable GST tool for everyday business tasks.
Use the Calculator
What Is a GST Calculator Australia (Free) – Add or Remove 10% GST Instantly?
GST (Goods and Services Tax) is a broad-based consumption tax of 10% on most goods and services sold or consumed in Australia. Introduced on 1 July 2000, it replaced the old wholesale sales tax and is collected by businesses on behalf of the Australian Taxation Office (ATO).
Who must register for GST:
Any business with a GST turnover of $75,000 or more per year (or $150,000 for not-for-profits) must register for GST. Taxi and rideshare operators must register regardless of turnover.
Two key concepts:
- Ex-GST price — the price before GST is added (the net amount)
- GST-inclusive price — the total amount including GST (what customers pay)
The 1/11 rule: The GST component is always exactly one-eleventh (1/11) of the GST-inclusive price. This is the fastest mental arithmetic shortcut for GST calculations.
Formula
Two formulas cover every GST scenario you’ll encounter:
Adding GST to an ex-GST price: GST-Inclusive Price = Ex-GST Price × 1.10 GST Amount = Ex-GST Price × 0.10 Removing GST from a GST-inclusive price: Ex-GST Price = GST-Inclusive Price ÷ 1.10 GST Amount = GST-Inclusive Price ÷ 11
Example Calculation
An electrician quotes $2,500 ex-GST for a job. The invoice sent to the client:
| Labour and materials (ex-GST) | $2,500.00 |
| GST (10% of $2,500) | $250.00 |
| Total invoice (GST-inclusive) | $2,750.00 |
| GST as fraction of total | 1/11 = 9.09% |
| For 3 invoices of this size | $8,250 total / $750 GST |
What Is a Good Result?
Common GST scenarios and quick reference calculations:
| Scenario | Ex gst | Gst | Inc gst |
|---|---|---|---|
| Standard quote / invoice | Your rate | × 0.10 | × 1.10 |
| Extract GST from receipt | ÷ 1.10 | ÷ 11 | Total paid |
| $1,000 ex-GST | $1,000.00 | $100.00 | $1,100.00 |
| $5,500 GST-inclusive | $5,000.00 | $500.00 | $5,500.00 |
| Monthly $10K retainer | $10,000.00 | $1,000.00 | $11,000.00 |
How to Improve Your Results
The ÷11 Mental Arithmetic Shortcut
To quickly find the GST component in any GST-inclusive price, **divide by 11**. A $1,100 total ÷ 11 = $100 GST. A $5,500 receipt ÷ 11 = $500 GST. This works because GST is always exactly 1/11th of the total price.
Always Show Both Amounts on Tax Invoices
A valid **tax invoice** (required for purchases over $82.50 GST-inclusive) must clearly show the GST amount separately. Invoices under $1,000 can show the total and state 'total price includes GST of $X'. Over $1,000, the GST breakdown is mandatory for the recipient to claim input tax credits.
Lodge Your BAS on Time
Most small businesses lodge BAS **quarterly** — due 28 days after the end of each quarter (with an extra 2 weeks if lodging through a registered tax agent). Late lodgement incurs failure-to-lodge penalties. Set calendar reminders for each BAS due date.
Know What's GST-Free
Not all goods and services attract GST. **GST-free supplies include:** most basic food (but not hot food, restaurant meals, or snacks), most health and medical services, most education services, some medications, and exports. Always check the ATO website for your specific situation.
Claim Input Tax Credits on Business Purchases
If you're GST-registered, you can **claim back the GST** you pay on business purchases as input tax credits in your BAS. This makes GST cost-neutral for registered businesses — you only remit the net difference between GST collected and GST paid.
Frequently Asked Questions
1What is the GST rate in Australia?
Australia’s GST rate is a flat **10%** on most goods and services. It has remained at 10% since its introduction on 1 July 2000 under the Howard government.
2How do I calculate GST in Australia?
**Adding GST:** Multiply the ex-GST price by 1.10 (e.g., $2,000 × 1.10 = $2,200 inc-GST). **Removing GST:** Divide the inc-GST total by 1.10 or use the 1/11 rule (e.g., $2,200 ÷ 11 = $200 GST; $2,200 − $200 = $2,000 ex-GST).
3What turnover threshold requires GST registration?
You must register for GST if your **annual GST turnover is $75,000 or more** ($150,000 for not-for-profit organisations). Turnover includes sales of goods and services but excludes input-taxed supplies like residential rent and financial services. Taxi and rideshare operators must register regardless of turnover.
4What items are GST-free in Australia?
Key GST-free categories include: **most basic food** (unprocessed, not hot food, not restaurant meals), most health and medical services, childcare, most education and training, some prescription medications, and goods exported from Australia. Residential rent and most financial services are ‘input-taxed’ — no GST charged, no input credits claimable.
5How often do I need to lodge a BAS?
Most small businesses lodge **quarterly BAS** (Business Activity Statement). Large businesses with annual turnover above $20 million lodge monthly. Very small businesses may be eligible for annual lodgement. Quarterly BAS is due **28 days after the end of each quarter**: 28 October, 28 February, 28 April, and 28 July.
Conclusion
Whether you’re quoting a job, reconciling receipts, or preparing your BAS, bookmark this free Australian GST calculator for instant use whenever you need to add or remove 10% GST — no registration, no fuss, always accurate.