GST Calculator

Adding and Removing GST

Australian GST is 10% of the price before GST. To add GST, multiply the exclusive price by 0.10. Add that GST amount to the price to find the invoice total.

To remove GST from a wholly taxable inclusive total, divide the total by 11 to find its GST component. Subtract that component to find the amount before GST. Dividing the inclusive total by 1.10 gives the unrounded exclusive amount.

For an AUD $110 inclusive total, the correct GST component is AUD $10. Subtracting 10% of AUD $110 would remove AUD $11 and leave AUD $99, which is incorrect.

Plus GST, add GST and ex GST start from the exclusive price. Invoice abbreviations excl. and ex mean excluding GST. Less GST, remove GST and reverse GST start from the inclusive total. Incl. and inc mean including GST.

Before GST is the net price. Including GST is the gross invoice total. The GST component sits between them. Copy this invoice calculation table into your workpaper.

In Excel, put the entered amount in A2 and the rate as a percentage in B2, such as 10%. For an exclusive amount, GST is =ROUND(A2*B2,2). The total is =A2+ROUND(A2*B2,2).

For an inclusive amount, GST is =ROUND(A2*B2/(1+B2),2). The amount before GST is =A2-ROUND(A2*B2/(1+B2),2). These formulas keep the entered side unchanged and round the GST component to cents, matching the calculator.

A Worked Invoice Amount

In this fictional invoice, a business charges AUD $1,250 before GST for a wholly taxable service. GST is AUD $125 and the invoice total is AUD $1,375. Enter AUD $1,375 with Remove GST selected to see those figures together.

Choose Add GST and enter AUD $1,250 to reach the same result. Before GST remains AUD $1,250, the GST component is AUD $125 and Including GST shows AUD $1,375.

The calculator rounds GST to the nearest cent, with half a cent rounded upwards. It then adds or subtracts that rounded GST so the displayed amounts balance. The GST Act’s calculation and rounding rules set the ordinary rate and invoice treatment.

For a fictional Uber driver’s workpaper, assume AUD $1,100 of entered fares are wholly taxable and AUD $220 of entered fees are eligible taxable purchases. The Australian sales and purchases section shows AUD $100 sales GST, AUD $20 purchase GST and AUD $80 net GST.

Use the driver’s established taxable fare and fee figures. A net bank payout can combine amounts with different treatment, so it does not replace those figures. The calculator has no connection to Uber.

For a fictional car invoice, enter AUD $55,000 of taxable consideration including GST and an independently established 80% business-use share. Vehicle invoice GST is AUD $5,000. The business-use share of that component is AUD $4,000.

The business-use share is separate from the GST credit you can claim. Registration, creditable purpose and any applicable car credit cap still govern entitlement. The ATO’s GST and motor vehicles guidance explains those limits. Enter only taxable consideration, excluding charges without GST.

Rounding each invoice line can produce a different total from rounding once. Two lines of AUD $0.06 including GST each produce AUD $0.01 GST when rounded separately. Their AUD $0.12 combined total produces AUD $0.01 GST when rounded once. The AUD $0.01 difference comes from when rounding occurs.

When the Arithmetic Does Not Decide Tax Treatment

The Australian sections assume every entered amount is wholly taxable at the ordinary Australian rate. That assumption does not establish whether the supplier is registered or required to register. The government’s GST registration guide explains when registration applies.

GST-free and input-taxed supplies have no GST on the sale. Related purchases can generally carry GST credits for GST-free supplies, while purchases used to make input-taxed supplies generally cannot. The ATO explains these types of sales.

Separate taxable amounts from GST-free or input-taxed amounts before entering a mixed invoice. Special rules, including the property margin scheme, need a separate calculation. An entered foreign rate checks a price split only. It does not determine overseas registration, exemptions, supply classification or multi-component liability.

Reconcile a Transaction Total

Paste selected taxable amounts as one column, with one amount per line. Tabs or semicolons also separate amounts. Commas are thousands separators, so 1,375.00 is one amount. Use the same inclusive or exclusive basis for every selected amount.

Choose Separate invoices when each entry is a wholly taxable invoice total. The calculator rounds each invoice’s GST before adding it. For taxable amounts from one invoice, choose One invoice to add the unrounded GST and round once.

The example list contains AUD $1,375, AUD $82.50 and AUD $165 including GST. Their combined amount is AUD $1,622.50 and calculated GST is AUD $147.50. Comparing that with AUD $147.50 in the BAS workpaper gives an AUD $0.00 difference.

Enter the workpaper’s GST for exactly those selected amounts, before whole-dollar BAS reporting. A positive difference means calculated GST is higher. A negative difference means the entered workpaper amount is higher.

For a sole trader, small business or tradie, the separate sales and purchases section subtracts purchase GST from sales GST. Its example uses AUD $1,375 taxable sales and AUD $275 eligible purchases, both inclusive. Sales GST is AUD $125, purchase GST is AUD $25 and Net GST workpaper amount is AUD $100.

Net GST workpaper amount compares sales and purchases. Before GST means the net price of one invoice. These are different calculations. Enter only purchases whose credit eligibility and business-use treatment you have already established.

Compare the rounding method with the source invoices. This arithmetic check excludes credit notes, adjustments and partial GST credits. It does not classify unknown supplies, establish GST-credit entitlement or calculate the final BAS payment.

The calculator uses only the amounts you enter in this page. It changes no connected ledger, sends no amounts to Tax Genie or the ATO and saves none in browser storage.

Australian Sales and Purchase GST

Australian sales tax and purchase tax mean GST in this calculator. Use Add GST for a taxable sales or eligible purchase price before GST. Use Remove GST when the entered amount already includes GST.

The selected-transactions comparison, sales and purchases section and vehicle section always use Australian GST at 10% in AUD. The single-invoice rate and currency settings do not change them. Overseas state and local sales-tax schedules are outside this calculation.

Goods and Services Tax

GST means goods and services tax. The same entered figure gives different answers depending on its GST basis. At 10%, AUD $110 excluding GST has AUD $11 GST and an AUD $121 total. AUD $110 including GST has AUD $10 GST and an AUD $100 price before GST.

Choose the Rate and Currency

The single-invoice calculation starts at the Australian rate of 10%. For a cross-border invoice, enter the percentage you have already established and select the invoice’s currency label. The label changes no exchange rate and converts no amount.

For a fictional New Zealand invoice with an established 15% rate, enter NZD $1,150 and choose Remove GST. GST is NZD $150 and Before GST is NZD $1,000. Add GST to NZD $1,000 at 15% to recover NZD $1,150.

The same entered-rate arithmetic supports India and Singapore invoices. For fictional established rates, INR 1,000 before GST at 18% produces INR 180 GST and INR 1,180 including GST. SGD $1,000 before GST at 9% produces SGD $90 GST and SGD $1,090 including GST. Currency selection never chooses the applicable rate.

NSW, Victoria, South Australia, WA and Queensland use the same Australian GST arithmetic. Sydney, Melbourne, Adelaide, Perth and Brisbane add no separate city rate. A year such as 2025 or 2026 does not silently select a different rate.

For import duty and import GST, use the import tax calculator.

Check Another Calculator’s Result

Match the entered price, rate and GST basis before comparing results. Xero’s public GST calculator describes adding 10% to an exclusive price and removing GST from an inclusive total. At 10%, the AUD $1,250 exclusive example produces AUD $125 GST and an AUD $1,375 inclusive total by those formulas.

A public calculator result checks that price split. A connected Xero ledger balance also depends on the transactions, tax treatment and reporting period recorded there.

Moneysmart, also searched as Money Smart, publishes the same Australian multiply-by-1.1 and divide-by-11 assumptions. Under those assumptions, AUD $1,375 including GST contains AUD $125 GST. Omni describes the net-price, entered-rate and gross-price relationship too.

For a result from Omni or Stuff, use the same amount, entered percentage and inclusive or exclusive basis. Applying 10% to AUD $1,250 before GST gives AUD $125 GST and AUD $1,375 including GST. Different rates or rounding methods can explain a different answer.

This free online calculator runs in phone and desktop browsers without a download, account or client-data upload. Use the business expense tool for expense-record checks and categorised totals before selecting amounts for a GST workpaper.