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GST calculator for tradie quotes

Add GST to a quote or strip it back out. Enter the amount you have and this shows the ex GST figure, the GST component and the inc GST total at the Australian rate of 10%.

Total including GST --
Excluding GST--
GST component--

Australian GST at 10%. This is a maths tool, not tax advice.

The maths

Australian GST is 10%, which makes both directions straightforward:

adding GST: total = amount × 1.1
removing GST: amount = total ÷ 1.1

Removing GST is where people slip up. You do not take 10% off a GST-inclusive figure, you divide by 1.1. Taking 10% off $25,300 gives $22,770, which is wrong. Dividing by 1.1 gives $23,000, which is right.

A quick shortcut for the GST component of an inclusive figure: divide by 11.

A worked example

You have priced a job at $23,000 before GST.

  • GST: $23,000 × 0.10 = $2,300
  • Total the client pays: $25,300
  • Working backwards from $25,300: $25,300 ÷ 11 = $2,300 GST, leaving $23,000

Getting GST right on a quote

  • Say which one your price is. Every quote should state plainly whether the figure includes or excludes GST. Most disputes about GST are really disputes about an ambiguous quote.
  • Do not take 10% off to remove it. Divide by 1.1, or divide by 11 to get the GST portion on its own.
  • Apply your margin before GST, not after. GST is not revenue, it is collected and passed on.
  • Residential clients read the inc GST number. A homeowner comparing quotes is looking at the total they pay, so showing it avoids a nasty surprise at the end.

Whether you charge GST at all depends on your registration and circumstances. If you are not sure where you stand, check with your accountant or the ATO rather than a calculator.

Doing this on every job?

BuildScope can show or hide GST on a quote, so you can send a residential client the inc GST total and hand a builder the ex GST figure without rebuilding the document.

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How do I remove GST from a total?
Divide the GST-inclusive amount by 1.1. To find the GST component on its own, divide the inclusive amount by 11. Subtracting 10% from an inclusive figure gives the wrong answer, because the 10% was calculated on the smaller ex GST amount rather than the total.
Should a tradie quote include GST or exclude it?
Either is fine as long as the quote says clearly which it is. Residential clients usually want to see the total they will pay, so inc GST tends to suit them. Commercial clients and builders often work in ex GST figures. What causes arguments is leaving it unstated.
What is the GST rate in Australia?
GST is 10% on most goods and services, including the majority of construction and trade work. Some supplies are GST-free or input-taxed, and whether you charge it depends on your own registration, so check your circumstances rather than assuming.
Do I add my margin before or after GST?
Before. Work out your cost, apply your margin to get the sell price, then add GST to that figure. GST is collected on behalf of the ATO and passed on, so treating it as part of the amount you are making will overstate your profit.
Is this calculator tax advice?
No. It performs the arithmetic at the standard 10% rate. Whether GST applies to your work, whether you are required to be registered, and how you report it are questions for your accountant or the ATO.

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Maintained by Ben Hinkley, Senior Estimator · Last updated