GST Calculator — Free Online Tool
Add GST to a net amount or remove GST from a gross amount in one click.
About GST Calculator
The GST Calculator works in two directions: it can add GST to a net amount to give you the gross price, or remove GST from a gross price to reveal the original net amount. Either way you get a full breakdown of the net amount, the GST portion and the gross total.
It is handy for invoicing, expense claims, pricing products and double-checking receipts at any GST rate you enter. Calculations are immediate and happen entirely on your device, keeping your figures private.
How to Use GST Calculator
- Choose whether to add GST (exclusive amount) or remove GST (inclusive amount).
- Enter the amount you are working from.
- Type in the GST rate as a percentage.
- Click "Calculate" to see the net amount, GST amount and gross total.
Key Features
Add GST to a net price or remove it from a gross price
Full breakdown of net, GST and gross amounts
Works with any GST rate you enter
Validates amounts and rates before calculating
Runs locally in your browser for privacy
Frequently Asked Questions
What is the difference between adding and removing GST?
Adding GST treats your amount as the pre-tax (net) value and calculates the tax on top. Removing GST treats your amount as the tax-inclusive (gross) value and works backwards to find the net amount.
How do I remove GST from a total?
Divide the gross amount by 1 plus the rate as a decimal. For 18% GST, divide by 1.18 to get the net amount; the difference is the GST. This tool does it automatically.
Can I use any GST rate?
Yes. You can enter whatever rate applies to your goods or region, such as 5%, 12%, 18% or 28%.
Is the GST amount rounded?
Results are shown to two decimal places for currency, while the underlying calculation uses full precision.