About this tool

GST Calculator Australia

Add or remove Australia's 10% GST using the divide-by-11 rule, with a BAS summary and the $75,000 registration check.

This calculator adds Australia's 10% GST to a price or takes it back out using the ATO's divide-by-11 rule. Adding GST multiplies the exclusive price by 1.1; removing it divides the inclusive price by 11 to get the tax, because one eleventh of a GST-inclusive amount is exactly the GST. It also builds a BAS summary — G1 total sales, 1A GST on sales, 1B GST credits on purchases — and checks the $75,000 registration threshold.

How to use GST Calculator Australia

1. 1

   Open GST Calculator Australia on AltFTool — it loads instantly in your browser.

2. 2

   Enter the values you already know.

3. 3

   Fine-tune the options to match your scenario.

4. 4

   Read the result and use it in your planning or reporting.

Why use GST Calculator Australia

• The divide-by-11 rule

  Extracts GST from an inclusive price exactly, instead of wrongly subtracting 10%.

• BAS labels, not just numbers

  Maps the result to G1, 1A and 1B so it transfers straight onto the statement.

• Treatment aware

  Handles GST-free and input taxed supplies, which carry no GST at all.

Common use cases

• Setting a shelf price: a $100 GST-exclusive item becomes $110 including GST, and the $10 difference is what you report at 1A.
• Reading a $99.95 tax invoice and recording $90.86 as the expense and $9.09 as the GST credit at 1B.
• Preparing a quarterly BAS: $55,000 of sales gives $5,000 at 1A, $22,000 of purchases gives $2,000 at 1B, leaving $3,000 payable.

Frequently asked questions