Made in Melbourne
Australian GST calculator.
Add or remove 10% GST as you type. Exact to the cent, free forever, and nothing you enter ever leaves your browser.
- Before GST
- $100.00
- GST 10%
- $10.00
- Including GST
- $110.00
Calculated in your browser, in whole cents — the three figures always add up.
- InstantWorks as you type. No button, no waiting, no page reload.
- Exact to the centCalculated in whole cents, so the figures always reconcile.
- Nothing uploadedRuns entirely in your browser. No account, no tracking of what you type.
- Built for Australia10% GST, the divide-by-eleven rule, and ATO invoice requirements.
The two sums people need
Adding GST
You have a price before GST and need the total to charge. Multiply by 1.1. A $250 service becomes $275, of which $25 is GST.
Removing GST
You have a total that already includes GST and need the GST portion. Divide by 11. A $550 invoice contains $50 of GST and $500 before GST.
Eleven surprises people who expect ten. The total is 110% of the original price, so the GST is one eleventh of the total, not one tenth.
Worked examples
| Before GST | GST | Total |
|---|---|---|
| $10.00 | $1.00 | $11.00 |
| $100.00 | $10.00 | $110.00 |
| $250.00 | $25.00 | $275.00 |
| $909.09 | $90.91 | $1,000.00 |
| $4,545.45 | $454.55 | $5,000.00 |
Notice the last two. A round total rarely has a round GST, which is why the calculator works in whole cents rather than dollars — so the figures on your invoice always add up.
What this tool will not do
It calculates. It does not advise. Whether you must register for GST, whether a particular sale is taxable, and how to lodge a BAS are questions for the ATO or a registered tax agent.
Once you have the figure
- Put it on a compliant document with the tax invoice maker.
- Verify a supplier’s number with the ABN check.
- Not sure whether you should be charging GST at all? When you have to register.
- Selling food or medical services? Some of it may be GST-free.
GST questions
How do I calculate GST in Australia?
GST is 10%. To add it, multiply the price by 1.1. To find the GST already inside a price, divide the total by 11. So a $110 total contains $10 of GST and $100 before GST.
How do I work out GST from a total?
Divide the GST-inclusive total by 11. That gives the GST portion. Subtract it from the total for the price before GST. This is the method the ATO uses, and it is why 11 rather than 10 is the number that matters.
What is the GST rate in Australia?
10% on most goods and services. It has been 10% since GST began on 1 July 2000. Some items are GST-free, such as most basic food, and some are input taxed.
Do I have to register for GST?
Registration is generally required once your business turnover reaches the ATO threshold, and is optional below it. Thresholds and rules change, so check ato.gov.au or ask a registered tax agent — this site calculates figures, it does not give tax advice.
Why does the GST come to an odd number of cents?
Because a tenth of many prices is not a whole cent. We calculate in whole cents and round half up, so the three figures always reconcile exactly. A $10 total contains $0.91 GST and $9.09 before GST — which adds back to $10.00.
Is this GST calculator free?
Yes, completely, with no account and no limit. It runs in your browser, so the amounts you type are never sent anywhere.
Can I use this for a tax invoice?
Yes. Once you have the figures, the tax invoice maker lays them out with the fields the ATO requires, including your ABN and the GST shown separately.