Free GST Calculator

Add GST to a price, or work backwards to remove GST from a total.

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GST / Tax Calculator

Calculate GST or sales tax on amounts

Results

Net Amount (excl. GST) $0.00
Tax Amount $0.00
Total (incl. GST) $0.00

About the GST Calculator

Australian GST is 10%, so adding GST means multiplying by 1.1 and removing GST means dividing by 1.1 — not subtracting 10%, which is the most common mistake. This calculator handles both directions and supports other rates.

Frequently Asked Questions

How do I add GST to a price?

Multiply the GST-exclusive amount by 1.1 for Australia’s 10% GST. For example, $100 plus GST is $110. This calculator does it for any rate you choose.

How do I remove GST from a total?

Divide the GST-inclusive total by 1.1, not subtract 10%. $110 including GST is $100 excluding GST, and the GST portion is $10. Subtracting 10% would incorrectly give $99.

When do I have to register for GST?

In Australia you must register for GST once your annual business turnover reaches $75,000. Below that, registration is optional. Confirm your situation with the ATO.

Is this GST calculator free?

Yes. It runs entirely in your browser with no signup and nothing is uploaded to a server.

Related Tools & Guides

Free Invoice Generator

Create GST-ready tax invoices

 Accounting & Finance Tools

Track expenses and cash flow

 How to Create a GST Invoice

Step-by-step ATO requirements

 GST for Small Business Australia

Complete GST guide
  • Switch Calculators: Click the tabs at the top to switch between GST/Tax, Markup vs Margin, Break-Even, and Loan Repayment calculators.
  • GST Calculator: Enter an amount, choose "Add GST" or "Remove GST", and select a tax rate preset or enter a custom rate. Results update instantly.
  • Markup vs Margin: Enter your cost and selling price to see both markup percentage and margin percentage side by side. Understand the difference for better pricing.
  • Break-Even Analysis: Enter your fixed costs, price per unit, and variable cost per unit to find how many units you need to sell to break even.
  • Loan Calculator: Enter the loan amount, interest rate, and term to see your monthly payment, total interest, and amortisation breakdown.
  • Real-Time Results: All calculators update as you type — no need to click a "Calculate" button.
  • Copy Results: Use the Copy button (where available) to quickly copy calculated values to your clipboard.
  • No Data Stored: These calculators don't save any data. They run entirely in your browser for privacy.