US Sales Tax Calculator
An easy online sales tax calculator for the United States. Instantly add or reverse sales tax using state averages or custom rates.
Calculation Mode
Amount ($)
State (Average Rate)
*Average combined state & local tax rate
Exact Tax Rate (%)
Enter an amount above to see the sales tax calculation.
How the Sales Tax Formula Works
This tool uses standard formulas to add or extract sales tax dynamically:
Adding Sales Tax (Exclusive)
Tax Amount = Base Price × Tax Rate ÷ 100
Extracting Sales Tax (Inclusive / Reverse)
Base Price = Total Amount ÷ (1 + (Tax Rate ÷ 100))
Frequently Asked Questions
How does US Sales Tax work?
In the United States, there is no federal sales tax. Instead, sales tax is imposed at the state level, and often supplemented by local (county and city) taxes. This means the total sales tax rate can vary significantly depending on where you are.
How do you calculate sales tax?
To calculate sales tax, multiply the price of the item by the tax rate as a decimal. For example, if the item is $100 and the sales tax rate is 8.25%, the calculation is $100 × 0.0825 = $8.25 in tax. The total is $108.25.
Can I reverse calculate sales tax?
Yes, if you have the total price and the tax rate, you can find the original price before tax. Divide the total price by 1 + the tax rate as a decimal. For a total of $108.25 and an 8.25% rate, calculate $108.25 ÷ 1.0825 = $100.
Are the state average rates exact?
The state rates provided in the dropdown are average combined state and local rates. For the exact rate, you must know the specific zip code, county, and city, as local municipalities can add their own taxes on top of the state rate.
Last updated: June 2025