Sales Tax Calculator

Sales tax and VAT formulas

A simple percentage tax is calculated from a base amount. To add tax, use tax = net amount × tax rate ÷ 100, then add the tax to get the gross total. If an item costs 100 before tax and the rate is 8.25%, the tax is 8.25 and the total is 108.25. This is the common calculation for sales tax, VAT, GST and other straightforward percentage taxes when a single rate applies to the full amount.

Removing tax reverses the formula. When a displayed price already includes tax, the net amount is gross amount ÷ (1 + tax rate ÷ 100). The included tax is gross amount minus that net amount. This mode is useful for receipts, VAT-inclusive prices, marketplace listings or accounting notes where you need to separate the pre-tax subtotal from the included tax.

Using the calculator correctly

Choose add-tax mode when your amount is before tax, such as a subtotal in a shopping cart. Choose remove-tax mode when your amount already includes tax and you want the base price. The calculator does not know local rules, exemptions, city add-ons or product categories, so enter the exact rate that applies to your case. If several rates apply, calculate each taxable portion separately and add the results manually.

Rounding and privacy notes

Stores and tax agencies may round each line item, round at invoice level, or use special rules for cash payments. This page shows a clean mathematical estimate formatted as currency. It runs entirely in the browser and never sends prices, locations or purchase details to a server. For filing, invoicing or payment, follow the rounding and reporting rules required in your jurisdiction or accounting system.

Worked examples and a common mistake

Adding tax: a 49.99 subtotal at 7% gives tax of 3.4993, shown as 3.50, for a gross total of about 53.49. Removing tax: a VAT-inclusive price of 120 at 20% has a net amount of 120 ÷ 1.20 = 100, so the included tax is 20.

The most common mistake is taking the tax percentage directly from an inclusive price. Twenty percent of 120 is 24, but that is wrong because the 20% was applied to the net price, not to the total. In remove-tax mode the calculator divides by 1 plus the rate instead. Also remember that a rate of 8.25% is entered as 8.25, not 0.0825. The results show net, tax and gross separately, so you can copy each figure into a spreadsheet or invoice.