In Australia, GST (Goods and Services Tax) is a broad-based tax of 10% on most goods, services, and other items sold or consumed in the country. It has been in effect since 1 July 2000 and is administered by the Australian Taxation Office (ATO).
Whether you’re a business owner adding GST to your prices, a consumer wanting to know how much tax you’re paying, or an accountant preparing BAS (Business Activity Statements), a GST calculator is an essential tool.
Current GST Rate (as of November 2025)
Standard GST rate: 10%
Some items are GST-free (e.g., basic food, medical aids, education)
Some items are input-taxed (e.g., residential rent, financial services – no GST charged, but no input tax credits)
Common GST Calculations
Purpose
Formula
Example (Price = $100 excl. GST)
Add GST (calculate inclusive price)
Inclusive = Exclusive × 1.10
$100 × 1.10 = $110.00
Remove GST (extract GST amount)
GST Amount = Inclusive ÷ 11
$110 ÷ 11 = $10.00
Remove GST (calculate exclusive price)
Exclusive = Inclusive ÷ 1.10
$110 ÷ 1.10 = $100.00
Quick GST extraction (1/11th method)
GST = Total inclusive price ÷ 11
$110 ÷ 11 = $10.00
The “divide by 11” trick” works because GST is 10% of the GST-exclusive amount, which equals exactly 1/11th of the final GST-inclusive price.
Simple GST Calculator (Ready to Use)
Here are quick formulas you can copy into Excel, Google Sheets, or any calculator:
Description
Formula (if cell A1 has the amount)
Exclusive → Inclusive (add 10%)
=A1*1.1 or =A1+A1*0.1
Inclusive → Exclusive (remove 10%)
=A1/1.1 or =A1-A1/11
Extract only the GST amount
=A1/11 (from inclusive) or =A1*0.1 (from exclusive)
Online GST Calculator (Free & Reliable)
Australian Government business.gov.au calculator
Popular third-party sites: gstcalculator.com.au, calculator.com.au/gst, abettax.com.au/gst-calculator
GST Quick Reference Table
GST-Inclusive Price
GST Amount (÷11)
GST-Exclusive Price
$11.00
$1.00
$10.00
$55.00
$5.00
$50.00
$110.00
$10.00
$100.00
$275.00
$25.00
$250.00
$550.00
$50.00
$500.00
$1,100.00
$100.00
$1,000.00
Tips for Businesses
Always round to the nearest cent (0.5 cents rounds up).
If you’re registered for GST, you must include “Prices include GST” or show GST separately on tax invoices.
For exports and some business-to-business transactions, you can often charge GST-free.