How to use the GST calculator
Enter the amount, select the GST rate, and choose whether you want to add GST to a base amount or extract GST from a tax-inclusive amount.
GST calculation formula
GST amount when adding tax = Amount × GST rate ÷ 100. Final price = Amount + GST.
Common GST rates
This tool includes 5%, 12%, 18% and 28% as convenient calculator options. Confirm the applicable rate for your product or service before issuing an invoice.
Frequently asked questions
What is a GST calculator?
A GST calculator estimates the tax amount and total price from an entered amount and GST rate.
Can I remove GST from an inclusive amount?
Yes. Use the Remove GST option to calculate the pre-GST amount and GST component.