Use this simple calculator to add GST to a pre-tax amount or remove GST from a GST-inclusive price. Standard Australian GST is usually 10%.
General information only. Check with your accountant or the ATO for tax advice specific to your business.
How to use this Australian GST calculator
This tool helps you quickly work out GST for everyday pricing, invoices, and bookkeeping. Enter your amount, choose whether you want to add or remove GST, then click Calculate GST. The calculator instantly shows:
- GST-exclusive amount
- GST amount
- GST-inclusive amount
What is GST in Australia?
GST stands for Goods and Services Tax. In Australia, the standard GST rate is 10%. Businesses registered for GST generally include this tax on taxable sales and report it through their BAS (Business Activity Statement).
In practical terms, GST is often already built into retail pricing. For many business-to-business transactions, amounts may be listed as GST-exclusive and GST is added separately on the invoice.
GST formulas used by the calculator
1) Add GST to a GST-exclusive amount
If your amount does not include GST yet:
- GST amount = Amount × (GST rate ÷ 100)
- GST-inclusive total = Amount + GST amount
Example: $100.00 exclusive at 10% GST gives GST of $10.00 and a total of $110.00.
2) Remove GST from a GST-inclusive amount
If your amount already includes GST:
- GST-exclusive amount = Inclusive amount ÷ (1 + GST rate ÷ 100)
- GST amount = Inclusive amount − GST-exclusive amount
Example: $110.00 inclusive at 10% GST gives an exclusive amount of $100.00 and GST of $10.00.
When to add GST vs remove GST
Add GST when:
- You set prices internally before tax
- You prepare tax invoices from base costs
- You quote businesses with GST shown separately
Remove GST when:
- You receive a GST-inclusive total and need the pre-tax value
- You reconcile receipts for accounting software
- You split sale value and tax component for BAS reporting
Important GST notes for Australian businesses
Not every sale is treated the same for GST. While this calculator is great for standard taxable transactions, you should still understand the broader rules:
- GST-free supplies may include some basic food, health, and education items.
- Input-taxed supplies can include certain financial supplies and residential rent.
- Registration thresholds apply for when businesses must register for GST.
- Record keeping matters: keep valid tax invoices and receipts for compliance.
If a transaction is GST-free or input-taxed, a standard 10% calculation may not apply.
Quick GST examples
Example A: Freelancer invoice
You charge $2,500 for services (exclusive). Add 10% GST:
- GST: $250
- Total invoice: $2,750
Example B: Expense receipt analysis
You paid $55 for office supplies (inclusive). Remove 10% GST:
- Exclusive amount: $50
- GST component: $5
Final thoughts
A reliable GST calculator saves time and reduces spreadsheet mistakes. Whether you are a sole trader, contractor, startup founder, or small business owner, fast GST checks make invoicing and BAS preparation much easier. Bookmark this page and use it whenever you need a quick Australian GST breakdown.