How to use it
Pick what you want to do. Add tax to a price: enter the price before tax and the rate, and see the tax and the total. Remove tax from a price: enter a price that already includes tax, and the rate, and see the price without tax and the amount of tax in it. Find the tax rate: enter the price before and after tax and the tool works out the rate. Type the rate yourself, because sales tax and VAT rates depend on the place, the product and the date, and they change. The buttons offer a few common examples only. Your last rate and currency symbol are remembered on this device.
Adding and removing tax
To add tax, multiply the price by the rate and add the result: 8.25% on 100.00 is 8.25, so the total is 108.25. To remove it, do not just subtract the same percentage, because the rate applies to the price before tax. Divide the tax-inclusive price by one plus the rate (1.0825 here) to get 100.00 back. For example, a price of 120 with 20% VAT included contains 20 of tax, not 24. Amounts are rounded to the nearest cent after each step, which matches most shops, though some round on the total of a whole receipt, so the last cent can differ.
Questions
Is this tax advice? No, it only does the arithmetic from the rate you enter. Check the rules that apply to you with the tax authority. Can I use it for VAT, GST or any other sales tax? Yes, they all work as a percentage added to the net price. What about discounts? Take them off first, as shops do, with the Discount Calculator, which can also add tax. For splitting a bill, see the Tip & Bill Splitter.