Free Invoice Generator

GST calculator

Add GST to an amount, or take it back out of a total that already includes it. Removing GST is a division rather than a subtraction, which is where the figure usually goes wrong.

What you're working out
The amount

The figure you are charging before any GST is added.

Round numbers to save typing, not a list of rates you ought to be charging. Enter the rate that applies to your invoice.

Used only if you press Create this invoice, as the name of the line it becomes.

GuideHow VAT works (the same sum as GST)How this works, and where the figures go wrong →

What the GST calculator does not do

  • It does not know your GST rate, and there is no country list here on purpose. Rates differ by country and by what is being sold, and a table of them on this page would be tax advice that goes out of date the day a rate changes. Check the current rate with the tax authority, such as Inland Revenue in New Zealand or the CRA in Canada.
  • It does not split GST that is charged in two parts, such as a central and a state share, or a federal and a provincial one. For that, use the sales tax calculator: name each part as a row, give it its rate, and it divides the tax across them.
  • It does not decide whether you have to charge GST at all, or what your invoice must say to count as a tax invoice. Registration thresholds and invoice requirements are questions for your tax authority or your accountant.
  • It does not keep anything. Nothing is written to your browser's storage while you use it and nothing is sent to us, so the figures are gone when you close the tab. Press Create this invoice if you need a document: the figures are handed to the invoice generator in this tab, cleared as soon as it opens, and saved there as a new invoice alongside any you already have.

Related

Where the tax is called VAT, the VAT calculator is the same sum under that name. For a whole invoice rather than one amount, the invoice calculator takes line items, a discount and a deposit. The invoice requirements checker lists what a GST invoice must show in Canada, Australia and New Zealand, including the amounts at which the buyer's details become required, and the VAT number checker also checks an ABN or an NZ GST number against its published check digit.

Last updated 24 September 2026