🇦🇺 Australia

GST Calculator

Add or remove GST at the standard 10% rate, or estimate your net GST payable for a BAS period from total sales and purchases.

Add GST
Remove GST
BAS Estimate

Add GST to Price

Your Result

Enter an amount and click "Calculate" to see the breakdown.

Adding & Removing GST — The Two Formulas

Both directions come down to simple math, but people mix them up constantly:

A common mistake: taking 10% off a GST-inclusive total instead of dividing by 1.10 — this under-calculates the pre-GST price, since 10% of the total isn't the same as the GST component of that total.

BAS Estimate — For Business Owners

If you're GST-registered, your quarterly (or monthly) Business Activity Statement nets off GST you collected on sales against GST you paid on business purchases (input tax credits). This calculator's BAS Estimate mode does that calculation for you from two simple totals.

Worked Example

ItemAmount
Total sales, incl. GST$55,000
GST collected (1/11th of sales)$5,000
Total purchases, incl. GST$22,000
GST credits (1/11th of purchases)$2,000
Net GST payable to ATO$3,000

If your GST credits exceed GST collected — common for businesses with large capital purchases in a given period — you'd be due a refund instead of owing a payment.

GST-Free Items — Not the Same as GST-Exempt

Most basic food, many health and medical services, most education, and some childcare are GST-free. This is a specific legal category: a GST-free sale still lets the business claim input tax credits on related purchases, unlike a true "input-taxed" supply (like most financial services or residential rent), where no GST is charged and no credits can be claimed on related costs.

Registration Threshold

You must register for GST once your turnover reaches or is expected to reach $75,000/year ($150,000 for non-profit organisations). Below that, registration is optional — some small businesses register voluntarily anyway to claim input tax credits on setup costs.

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Frequently Asked Questions

How do I calculate GST on a price?+
To add GST, multiply the pre-GST price by 0.10 and add that to the original price, or simply multiply by 1.10. To remove GST from a GST-inclusive total, divide by 1.10 to find the pre-GST price.
What items are GST-free in Australia?+
Most basic food, many health and medical services, most education courses, and some childcare are GST-free. This is different from being GST-exempt for input tax credit purposes — GST-free supplies still let a business claim credits on related purchases.
When do I need to register for GST?+
You must register once your business's GST turnover reaches or is expected to reach $75,000/year ($150,000 for non-profits). You can also register voluntarily below that threshold if it benefits your business.
What's the difference between GST collected and GST credits?+
GST collected is the GST you charged customers on sales. GST credits (input tax credits) are the GST you paid on business purchases, which you can claim back. Your net GST payable to the ATO is collected minus credits.
NOTE

The BAS Estimate mode assumes all sales/purchases entered were fully GST-inclusive at the standard rate — actual BAS calculations may involve GST-free sales, input-taxed supplies, and adjustments not captured by this simplified estimate. Use accounting software or a BAS agent for your actual lodgment.