Work out sales tax in seconds. Enter a price and a tax rate to add the tax on top — or switch modes to find how much tax is already inside a total. It shows the price before tax, the tax amount and the final total, for any rate. It runs in your browser.
About this sales tax calculator
Sales tax (called VAT or GST in many countries) is a percentage added to the price of goods and services. This calculator works two ways. In add tax mode you enter a pre-tax price and a rate, and it shows the tax and the final total — useful for quoting a customer or budgeting a purchase. In amount includes tax mode you enter a total that already has tax in it, and it works backwards to show the original price and how much of the total is tax — handy for receipts and bookkeeping. It works with any rate, including ones with decimals like 8.25%, and all the maths runs in your browser.
State sales tax calculators
Preset to each state’s average combined rate (July 2026): California · Texas · Florida · New York · Pennsylvania · Illinois · Ohio · Georgia · North Carolina · Michigan.
Frequently asked questions
- How do I add sales tax to a price?
- Enter the price and the tax rate in "add tax" mode. The tool multiplies the price by the rate and shows the tax and the new total.
- How do I find the tax inside a total?
- Switch to "amount already includes tax" mode. The tool works backwards to show the pre-tax price and the tax portion of the total.
- Does it work for VAT or GST?
- Yes. Sales tax, VAT and GST are all percentage-based, so enter your local rate and the calculation is the same.
Understanding Sales Tax Calculations
Sales tax is calculated by applying a percentage rate to the base price of a transaction. The core formula for adding tax involves multiplying the base price by the tax rate expressed as a decimal and adding that result to the original amount. For example, a rate of six percent is treated as zero point zero six in calculations. This linear relationship ensures that the tax collected is directly proportional to the cost of the goods sold.
Reverse calculations are required when determining the pre-tax price from a total that already includes tax. This process requires dividing the total amount by the sum of one and the tax rate expressed as a decimal. The resulting quotient represents the original price, while the difference between the total and this quotient represents the tax amount. This approach is necessary because tax is calculated based on the original price rather than being a simple deduction from the final total.
A common error occurs when people attempt to subtract the tax percentage directly from the final total. If you take a total and subtract the tax rate as a percentage, you will arrive at an incorrect base price because you are applying the rate to the wrong number. The tax rate must always be applied to the pre-tax base value to reach the correct result. Always verify whether a given tax rate is a flat percentage or if it includes additional local surcharges that may apply to specific categories of items.