Free GST & Sales Tax Calculator
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About the GST / Tax Calculator
Add or remove GST, VAT or sales tax from an amount — enter a rate or pick a preset and see the tax and net or gross total instantly, all in your browser.
How to use the GST / Tax Calculator
- 1Choose whether to add tax to a net amount or remove it from a tax-inclusive amount.
- 2Enter the amount and pick a preset tax rate or type your own.
- 3See the tax amount and the net and gross totals instantly.
- 4Everything is calculated in your browser — nothing is uploaded.
Frequently asked questions
Is this GST / tax calculator free?
Yes — completely free, with no sign-up and no watermark.
Is my data uploaded anywhere?
No. All calculations run in your browser — nothing you enter is sent anywhere.
How do I add GST or sales tax to a price?
Use the “add tax” mode: enter the pre-tax (net) amount and the tax rate, and it shows the tax and the final tax-inclusive (gross) total. For example, adding 18% GST to 1,000 gives 180 tax and a 1,180 total.
How do I remove GST from a total that already includes it?
Use the “remove tax” mode: enter the tax-inclusive (gross) amount and the rate, and it works backwards to show the original net amount and the tax portion. It divides by (1 + rate), not just subtracting the percentage — which is the correct way to extract included tax.
Does it work for VAT and other sales taxes?
Yes — the maths is the same for any percentage-based tax like VAT, GST or general sales tax. Just enter the rate that applies to you, or type a custom one.