To calculate Canadian sales tax, first, you need to know both the federal goods and services tax (GST) rate, which is 5%. Then, you need to know if your province has a provincial sales tax (PST), and if it does, what is the rate. If you are a resident of Québec your provincial sales tax is called QST. To find your provincial sales tax rate, refer to our chart of sales tax rates by province or territory, located under the Canadian Sales Tax Calculator. If you would like to calculate sales tax yourself, you can use the following formula. Always convert the sales tax rate from a percentage to a decimal before plugging it into the formula. For example, if the sales tax rate is 5%, divide it by 100, and use 0.05 in your equation.   Purchase price x sales tax rate = amount of sales tax