GST calculator for Australia: add or remove 10% GST
GST in Australia is 10%. To add it, multiply the GST-exclusive price by 1.1: $1,250.00 becomes $1,375.00. To find the GST inside a GST-inclusive price, divide by 11: $1,375.00 contains $125.00 of GST and $1,250.00 before tax. Enter an amount, choose add or remove, and the calculator shows all three figures, plus a BAS estimate if you need it.
Amount including GST
$1,375.00
- Ex GST
- $1,250.00
- GST
- $125.00
Show breakdown
Calculation breakdown
- Ex GST
- $1,250.00
- GST
- $125.00
- Inc GST
- $1,375.00
| Ex GST | $1,250.00 |
|---|---|
| GST | $125.00 |
| Inc GST | $1,375.00 |
GST is 10% of the GST-exclusive price, or 1/11 of a GST-inclusive price.
At a glance
- GST rate
- 10% on most goods and services sold in Australia
- Add GST
- price × 1.1; GST amount = price × 0.1
- Remove GST
- GST = inclusive price ÷ 11; exclusive price = inclusive − GST
- Rounding
- GST to the nearest cent, half a cent rounds up; BAS in whole dollars
- Note
- Register for GST at $75,000 turnover ($150,000 for non-profits); ride-share drivers from the first dollar
- Note
- Tax invoice required for sales over $82.50 including GST
- BAS
- 1A GST on sales − 1B GST on purchases, plus PAYG withholding and instalments
How it is calculated
Add GST to an exclusive amount or divide an inclusive amount by eleven to extract ten per cent GST. For a BAS estimate, drop cents from GST labels and combine credits and withholding.
GST mode: add: gst = ex × 10%; inc = ex × 1.1
remove: gst = inc ÷ 11; ex = inc − gst (round gst to cents first, then ex = inc − gst so the two add back exactly)
BAS mode (whole dollars, cents dropped, per ATO instructions):
1A = floor((G1 − G3) ÷ 11)
1B = floor((G10 + G11 − purchases_without_gst) ÷ 11)
net GST = 1A − 1B
amount = 1A − 1B + W2 + 5A − 7D; payable if ≥ 0 else refund- Rates as at 2026-09-07 from Gst
How do you calculate GST in Australia?
GST is 10% of the price before tax, so adding it means multiplying by 1.1, and the GST amount is one tenth of the exclusive price. Working backwards from a GST-inclusive price is where people slip: the GST is one eleventh of the inclusive price, not one tenth, because the inclusive price is 110% of the base. A $1,375.00 invoice contains $125.00 of GST ($1,375 ÷ 11) and $1,250.00 before tax; taking 10% of $1,375 would give $137.50, which is wrong by $12.50. The calculator applies the right divisor in each direction and rounds to the cent the way the ATO specifies, so the exclusive price and the GST always add back to the inclusive figure exactly.
Which sales are GST-free or input taxed?
Most basic food, most health and medical services, most education courses, childcare, exports, and some other categories are GST-free: no GST is charged on the sale, but the seller can still claim credits on related purchases. Financial supplies and residential rent are input taxed: no GST on the sale and no credits on the inputs. Everything else sold by a registered business in Australia is taxable at 10%. Mixed invoices, a wholesaler selling both food and non-food lines for example, carry GST line by line, which is why the invoice generator on this site applies GST per line and why accounting systems need a tax code on every product.
How is a BAS calculated?
The business activity statement adds up the GST collected on sales (label 1A, which is total taxable sales ÷ 11), subtracts the GST paid on purchases that carry a credit (label 1B, purchases with GST ÷ 11), and adds any PAYG withholding from wages (W2), PAYG income tax instalment (5A) and other amounts, less fuel tax credits (7D). The result is payable if positive and refundable if negative. Amounts are reported in whole dollars. The estimate on this page uses those labels so it reads like the form, but it is an estimate: adjustments for private use, bad debts, the simplified GST methods for some retailers, and the choice between cash and accruals basis all change the real figures, which come from your accounting system.
When does a growing business need more than a GST calculator?
When GST is being worked out per line across hundreds of invoices, purchase orders and stock receipts a month, and the BAS is assembled from spreadsheets. Accounting software handles GST codes on transactions; the step beyond it is when inventory, purchasing and sales live in separate tools and the GST treatment of each line has to be re-keyed. An ERP carries the tax code on the product and the customer, applies it on every document, and produces the BAS labels from the ledger, which is the point at which the quarterly reconciliation stops being a project. That transition is what moving from Xero or AccountRight to an ERP looks like for most of the wholesalers we work with.
| Calculation | Input | GST | Result |
|---|---|---|---|
| Add GST | $1,250.00 ex GST | $125.00 | $1,375.00 inc GST |
| Remove GST | $1,375.00 inc GST | $125.00 | $1,250.00 ex GST |
| Remove GST, rounding | $99.99 inc GST | $9.09 | $90.90 ex GST |
| BAS estimate (quarter) | Sales $165,000 (of which $15,000 GST-free); purchases $66,000; W2 $9,800; 5A $4,200 | 1A $13,636 − 1B $6,000 | $21,636 payable |
| BAS estimate (refund) | Sales $44,000; purchases $71,500 ($2,200 without GST); capital $33,000 included | 1A $4,000 − 1B $6,300 | $2,300 refund |
Frequently asked questions
How do I calculate GST from a GST-inclusive price?
Divide the inclusive price by 11 to get the GST, and subtract it to get the price before GST. $1,375.00 ÷ 11 = $125.00 GST, leaving $1,250.00. Do not take 10% of the inclusive price; that overstates the GST by a tenth. The calculator's "remove GST" mode does the division and the rounding.
When do I have to register for GST?
When your GST turnover reaches $75,000 a year ($150,000 for non-profit organisations), or from the start if you provide taxi or ride-sourcing services. You can register voluntarily below the threshold to claim credits on purchases. Once registered you must charge GST on taxable sales, issue tax invoices over $82.50 and lodge a BAS.
Is GST rounded up or down?
To the nearest cent, with exactly half a cent rounding up. On a tax invoice you can round each line's GST or the total taxable amount, but be consistent. On the BAS, amounts are reported in whole dollars with the cents dropped. The calculator follows both rules.
What is the difference between GST-free and input taxed?
GST-free sales (basic food, health, education, exports) carry no GST and the seller can still claim GST credits on related purchases. Input taxed sales (financial supplies, residential rent) carry no GST and the seller cannot claim credits on the inputs. Both are reported at different labels on the BAS.
moving from Xero or AccountRight to an ERP
When GST is applied per line across thousands of documents a month and the BAS is a spreadsheet, it is time for tax codes on every product and customer. That is an ERP conversation.
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