GST Calculator Australia — Add or Remove 10% GST
Add GST to a net price, strip it out of a receipt, or rebuild a full price from the GST figure alone. Results update as you type and follow ATO rounding rules.
Reading Your Result: Why GST Is 10% Going Up but 9.09% Coming Down
The rate is 10%, but it is always 10% of the GST-exclusive price. Once GST is inside a price, it makes up one-eleventh of that price. This is the source of the most common GST error in Australia: taking 10% off a receipt. On a $1,100 invoice, 10% is $110, but the real GST is $100. The $10 gap looks small, but over a quarter of purchases it overstates your GST credits on the BAS, and the ATO can reverse that in a review.
| Starting figure | Add GST (×1.1) | Remove GST (÷1.1) | GST difference |
|---|---|---|---|
| $82.50 | $90.75 | $75.00 | $8.25 vs $7.50 |
| $1,000.00 | $1,100.00 | $909.09 | $100.00 vs $90.91 |
| $5,000.00 | $5,500.00 | $4,545.45 | $500.00 vs $454.55 |
| $75,000.00 | $82,500.00 | $68,181.82 | $7,500.00 vs $6,818.18 |
The same number gives two different GST amounts depending on whether GST is already in it. Before you calculate, decide which kind of figure you have. A supplier quote marked "+GST" or "ex GST" needs Add GST. A receipt, a shelf price or a bank deposit from a customer needs Remove GST. The figure printed in the GST box of a BAS or on an invoice line needs Work back from the GST amount.
Four Real Situations and What the Numbers Mean
1. A tradie who quoted $4,800 and forgot about GST
If a registered business quotes a price with no mention of GST, that price is treated as GST-inclusive. Here the $436.36 comes straight out of profit, which falls by 36%. The fix costs nothing: write "$4,800 + GST" or "$5,280 incl. GST" on every quote.
2. A mixed shopping basket
Applying ÷11 to a whole receipt overstated the GST by 140%. If you claim business purchases from supermarkets, cafés or pharmacies, use the GST total printed on the tax invoice, or run each taxable line through the calculator with the treatment set to 10%. Lines that are GST-free go through at 0%.
3. A $1,650 laptop: registered versus unregistered buyer
| Buyer | Paid at checkout | GST credit on BAS | Real cost |
|---|---|---|---|
| GST-registered business | $1,650.00 | $150.00 | $1,500.00 |
| Unregistered sole trader | $1,650.00 | $0.00 | $1,650.00 |
| Private consumer | $1,650.00 | $0.00 | $1,650.00 |
For a registered business, GST on business purchases is a timing cost, not a real one: it is paid at checkout and recovered at the next BAS. Income-tax deductions for that business are also based on the $1,500 GST-exclusive price, not on $1,650. Because the purchase is over $82.50, the credit can only be claimed with a valid tax invoice. Over $1,000, the invoice must also show the buyer's name or ABN.
4. A cash sale at the counter
Cash rounding moves the total by no more than 2 cents. Since 1 January 2026, larger fuel and grocery retailers must accept cash for in-person purchases up to $500, so rounding now comes up more often at the till. Select Cash — total to nearest 5c in the calculator to see the amount actually received and the GST it contains.
Does Registering for GST Pay Off Below $75,000?
You must register once your GST turnover reaches $75,000 ($150,000 for non-profits). Taxi and rideshare drivers must register from their first dollar, whatever their turnover (see GST for rideshare drivers). Below the threshold, registration is optional. Whether it helps or hurts depends almost entirely on who your customers are. The example below uses one business at $60,000 a year with $15,000 of GST-inclusive expenses.
| Option | Revenue kept (ex GST) | Business costs (net) | Result before income tax |
|---|---|---|---|
| Not registered | $60,000.00 | $15,000.00 | $45,000.00 |
| Registered, prices unchanged (consumers) | $54,545.45 | $13,636.36 | $40,909.09 |
| Registered, prices +10% (business clients) | $60,000.00 | $13,636.36 | $46,363.64 |
If you sell to consumers and the market will not take a 10% price rise, registering early costs this business $4,090.91 a year, about 6.8% of turnover. If you sell to GST-registered businesses, they recover the extra 10% as a credit. You can then raise prices without them feeling it, and you come out $1,363.64 ahead through the credits on your own costs. Use the GST registration checker to estimate when you will cross the threshold.
GST and Cash Flow: The Money in Your Account Is Not All Yours
Every GST-inclusive deposit contains one-eleventh that belongs to the ATO. If you treat it as income, the shortfall shows up at BAS time. Take a business with $33,000 of GST-inclusive sales and $11,000 of GST-inclusive costs in a quarter. It collects $3,000 in GST, can claim $1,000 in credits, and owes $2,000 at the end of the quarter.
GST in 2025 vs 2026: What Changed and What Did Not
| Rule | 2025 | 2026 |
|---|---|---|
| Standard GST rate | 10% | 10% |
| Registration threshold (business / non-profit) | $75,000 / $150,000 | $75,000 / $150,000 |
| Tax invoice needed to claim a credit | Over $82.50 | Over $82.50 |
| Buyer identity or ABN on tax invoice | $1,000 or more | $1,000 or more |
| Cash acceptance for fuel and groceries | Not required | Required from 1 Jan 2026, in person, up to $500 |
| Employee super payments | Quarterly | Each pay cycle from 1 Jul 2026 |
The GST formula itself has not changed since GST started in 2000, so any calculation above still works for 2026. What has changed is what surrounds it. The cash mandate covers fuel and grocery retailers with turnover of $10 million or more, plus smaller stores that share a brand with a larger chain. For these businesses, 5-cent rounding becomes part of daily GST reporting. Payday Super changes when money leaves the business account, not how GST is calculated. For the full rules, see the ATO's GST guidance.