How to add or remove GST
- Choose Add tax for a price before GST, or Remove tax for a GST-inclusive price.
- Australia's 10% rate is selected; switch to New Zealand (15%), Singapore (9%), India (18%), a Canadian province's GST or HST, or type any rate.
- Read the amount excluding GST, the GST and the total. Paste a list of prices to convert them all at once.
GST formulas
To add GST, multiply the price by one plus the rate: at 10%, 100 becomes 110. To find the GST inside a GST-inclusive price, divide by 1.1 and subtract, or use the shortcut that GST is one-eleventh of the total at 10%: 110 ÷ 11 = 10. In New Zealand, at 15%, GST is three-twenty-thirds of the inclusive price. Subtracting 10% from an inclusive price is a common mistake that gives the wrong answer.
Goods and services tax works like VAT: registered businesses charge it on sales, claim credits for GST paid on purchases and pass on the difference. In Canada, federal GST is 5%, and several provinces combine it with provincial tax into a harmonised sales tax (HST) of 13–15%; others add a separate provincial sales tax. India uses several GST slabs depending on the goods or service. Rates shown are standard rates published in 2025, so check your tax authority for current rates and exemptions. Calculations run in your browser and round to the cent per line, as on most tax invoices.
FAQ
How do I calculate GST in Australia?
Multiply by 1.1 to add GST. Divide a GST-inclusive price by 11 to find the GST in it.
What is the GST rate in New Zealand?
15%. Multiply by 1.15 to add it and divide by 1.15 to remove it.
What is HST in Canada?
Harmonised sales tax: federal GST and provincial sales tax combined into one rate, such as 13% in Ontario.