Remove Australian GST from a GST-inclusive total and calculate the net amount.
Reverse GST Calculator Australia
Use this Australia GST page when the total already includes GST and you need to work backwards to the pre-GST amount.
Rates are presets for quick estimates. Local, state, province, product, and invoice rules can vary, so replace the rate when your source shows a different value.
At 10% tax, $120.00 gross equals $109.09 before tax and $10.91 tax. View calculation formula
Remove tax from a total
Net price = gross total / (1 + GST rate / 100). The tax amount is the gross total minus the net price.
120 at 20% becomes 100 + 20
If the total is 120 and the tax rate is 20%, the pre-tax amount is 100 and the tax amount is 20.
Use the exact rate
Some countries, states, provinces, and products use reduced or combined rates. Change the rate when your invoice uses a different one.
reverse GST calculator Australia
Built for Australia tax-inclusive prices
Use this Australia GST page when the total already includes GST and you need to work backwards to the pre-GST amount.
Example at 10% Standard GST
A$110.00 total becomes A$100.00 before tax
- Tax-inclusive total
- A$110.00
- Pre-tax amount
- A$100.00
- GST amount
- A$10.00
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Australia GST rate source
The default rate is 10% Standard GST.
If a reduced, local, or product-specific rate applies, edit the rate before using the result.
Australia uses GST rather than VAT. The reverse formula is the same for GST-inclusive prices.
Source: Australian Taxation Office
Last verified: 2026-06-23
FAQ
What GST rate does this Australia calculator use?
It defaults to 10% Standard GST. If your invoice uses a reduced or special rate, enter that rate manually.
Can I use this for Australia invoices?
Yes, for quick calculation support. Use the exact tax rate shown on the invoice and confirm compliance details with official guidance or an accountant.
Does this page include historical GST rates?
No. It focuses on the current default rate and lets you enter a custom rate when an older or special rate applies.
What is a reverse tax calculator?
A reverse tax calculator works backwards from a tax-inclusive total to estimate the pre-tax price and tax amount.
Is this tax advice?
No. This site provides calculation help only. Check official tax guidance or a qualified professional for compliance decisions.
Can I use a custom tax rate?
Yes. Enter any tax rate between 0 and 100 to match your invoice, country, state, province, or product category.
Results are for calculation support only and do not replace official tax rules, accounting advice, or professional tax guidance.