GST Calculator FY2026-27
Every rate here checked against its official source on or after 2026-08-19 — per-source dates listed below.
GST in Australia is a flat 10% on most goods and services. Enter any amount to add GST to a GST-exclusive price, or to work out how much GST is included in a GST-inclusive total — using the formulas the ATO and MoneySmart publish, with the rounding convention stated openly.
Calculate GST
Price including GST $1,100.00
Price excluding GST: $1,000.00
GST (10%): $100.00
Price including GST: $1,100.00
This is general information, not financial or tax advice — for how GST applies to your own sales or purchases, consider a registered tax agent or the ATO's guidance.
GST at common amounts
Both directions at common amounts, computed from the engine above — first adding GST to a GST-exclusive price, then breaking a GST-inclusive total apart.
| Price ex. GST | GST added | Price inc. GST |
|---|---|---|
| $50.00 | $5.00 | $55.00 |
| $100.00 | $10.00 | $110.00 |
| $250.00 | $25.00 | $275.00 |
| $500.00 | $50.00 | $550.00 |
| $1,000.00 | $100.00 | $1,100.00 |
| $5,000.00 | $500.00 | $5,500.00 |
| Price inc. GST | GST included | Price ex. GST |
|---|---|---|
| $110.00 | $10.00 | $100.00 |
| $550.00 | $50.00 | $500.00 |
| $1,000.00 | $90.91 | $909.09 |
| $1,100.00 | $100.00 | $1,000.00 |
| $2,200.00 | $200.00 | $2,000.00 |
How this is calculated
Two published formulas, used verbatim (both from ASIC MoneySmart's GST calculator — the calculator the ATO's own "How GST works" page links to):
- Adding GST — "to work out the cost including GST, you multiply the amount exclusive of GST by 1.1". This calculator computes the GST component first (10% of the exclusive price), then sums: $1,000.00 + $100.00 = $1,100.00.
- Extracting GST — "you divide a GST inclusive cost by 11 to work out the GST component". Equivalently, the exclusive price is the total divided by 1.1: a GST-inclusive $1,000.00 is $909.09 plus $90.91 of GST.
Rounding: every figure is rounded to the nearest cent, and the GST component is taken so that the exclusive price and the GST always add back exactly to the inclusive price — no cent ever goes missing between the three figures, even when the division lands on a repeating decimal (as it does for a GST-inclusive $1,000).
Sources
- ATO — How GST works (QC22411: the 10% rate, registration thresholds, GST-free and input-taxed sales) — verified 2026-08-19
- ASIC MoneySmart — GST calculator (the ×1.1 and ÷11 formulas; the calculator the ATO page itself links to) — verified 2026-08-19
- ATO Tax, Super + You — GST calculator (the $1,000 worked examples used as golden vectors) — verified 2026-08-19
Assumptions used here follow the same general approach as ASIC's MoneySmart calculators and may not reflect every personal circumstance — see "What this doesn't model" for specifics.
What this doesn't model
- GST-free and input-taxed sales. The figures assume the amount entered is fully taxable at 10% — if some or all of a sale is GST-free or input-taxed (both categories the ATO's "How GST works" page describes), its real GST is lower than shown.
- Any special GST calculation that doesn't take 10% of the full sale price — if a transaction uses a concession or special valuation rule, this simple flat-rate working doesn't apply to it.
- Multi-line invoices. This calculator works on a single amount; an invoice that rounds GST line by line can legitimately differ by a cent or two from a single-total working.
- Whether you should register for GST, charge it on a particular sale, or can claim a GST credit — those are eligibility questions, not price arithmetic (see the FAQ).
If any of these apply, the real GST on a transaction will differ from the figures above.
Frequently asked questions
How do I calculate GST in Australia?
GST is 10% of the GST-exclusive price. To add it, multiply the amount exclusive of GST by 1.1 — that is ASIC MoneySmart's published formula, and it is the calculation the ATO's own "How GST works" page points readers to. On a $100 sale, GST is $10.00 and the customer pays $110.00; on the ATO education site's $1,000 example, GST is $100.00 and the GST-inclusive price is $1,100.00. The same working scales to any amount because the rate is flat — there are no brackets, thresholds or phase-outs in the GST calculation itself. This calculator does exactly that arithmetic in both directions, rounding each figure to the nearest cent.
How do I work out how much GST is included in a price?
Divide the GST-inclusive price by 11 — MoneySmart's published shortcut for the 10% rate. A $110 total includes $10.00 of GST on a $100.00 base price. When the division doesn't land on a whole cent, this calculator rounds the GST-exclusive price to the nearest cent and takes the GST component as the exact remainder, so the two parts always add back to the price you entered: a GST-inclusive $1,000 splits into $909.09 plus $90.91 of GST. That last cent matters on tax invoices, which is why the rounding convention is stated openly in "How this is calculated" below rather than hidden.
Why does dividing by 11 work?
It's the same 10% rate looked at from the other side. A GST-inclusive price is the exclusive price multiplied by 1.1, so the exclusive price is always 10/11 of the total — and the GST component is the remaining 1/11. Dividing the total by 11 therefore isolates the GST in one step, which is exactly why MoneySmart publishes "divide a GST inclusive cost by 11" as the reverse formula. A quick sanity check with round numbers: $1,100 ÷ 11 = $100.00, which is precisely the GST this calculator adds to a $1,000 exclusive price. The shortcut only works while the rate is 10%; at any other rate the divisor would change, which is why this page states the rate it uses and when it was last verified.
Who needs to register for GST?
Per the ATO's "How GST works" page: businesses and other enterprises with a GST turnover of $75,000 or more must register, the threshold is $150,000 or more for non-profit organisations, and anyone providing taxi travel — including ride-sourcing — must register regardless of turnover. Once registered, a business includes GST in the price of its taxable sales, issues tax invoices, claims credits for the GST in its business purchases, and reports through activity statements. Below the threshold, registration is optional. This calculator doesn't assess whether you need to register — it only does the price arithmetic — so if you're near the threshold, check the ATO's registration pages or ask a registered tax agent about your specific situation.
Does every sale include GST?
No. The ATO's "How GST works" page is explicit that GST is a broad-based tax on most — not all — goods and services sold or consumed in Australia: some sales are GST-free, and others are input-taxed, and neither carries the 10% charge this calculator applies. This page deliberately doesn't reproduce the lists of which categories qualify, because they turn on definitions and conditions that belong with the source — check the ATO's guidance on GST-free and input-taxed sales for the current detail. The practical consequence for this calculator: the figures above assume the amount you entered is fully taxable at 10%. If part of a purchase is GST-free, the real GST component of the total will be smaller than the divide-by-11 working suggests.