Add or back out sales tax in one step — free, no sign-up, any state's rate. Enter an amount and your tax rate to see the tax and the total — or find the pre-tax price hidden inside a tax-included total.
General calculation only — sales-tax rules, exemptions, and what's taxable vary by state and product. Confirm your exact rate and rules with your state's department of revenue.
To add tax, multiply the price by the rate. To remove it — find the pre-tax amount inside a tax-included total — divide the total by (1 + the rate), not just subtract the rate. This calculator shows both so you don't overpay or undercharge.
Tax = Amount × rate · Pre-tax (from a total) = Total ÷ (1 + rate)
Sales tax is added to the price of an item: tax = price × rate, and total = price + tax (or, in one step, total = price × (1 + rate)). To find the tax on an $80 purchase at an 8% rate: $80 × 0.08 = $6.40 tax, for a total of $86.40.
If you know the total and need the pre-tax price, divide by (1 + rate). An $86.40 total at 8% is $86.40 ÷ 1.08 = $80.00 before tax, and the tax portion is the $6.40 difference. This is how you separate tax from a grand total on a receipt, or price an item so the round number is what the customer pays at the register.
The United States has no national sales tax. Rates are set by states and by local jurisdictions (counties and cities), so the combined rate depends on where the sale happens. Forty-five states and Washington, D.C. levy a statewide sales tax; five — Alaska, Delaware, Montana, New Hampshire, and Oregon — have no statewide sales tax (though some Alaska localities levy their own). Combined state-and-local rates commonly land anywhere from around 4% to over 10%. Always use the rate for the buyer's location, not a national average.
Use it to check a receipt, to add tax to a quote, or to back out the tax already baked into a total. For anything with legal or filing consequences, confirm the current rate with your state's department of revenue — rates and exemptions change.
Multiply the pre-tax amount by the tax rate (as a decimal) to get the tax, then add it to the amount for the total. This calculator does it instantly and also works backwards from a tax-included price.
Divide the tax-included total by 1 plus the rate — for 8.25%, divide by 1.0825. Subtracting the percentage gives the wrong answer. The last result above does this for you.
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Yes. The Sales Tax Calculator is completely free, runs in your browser, and never asks for a signup, email, or download. Enter your numbers and the result updates instantly.
It uses standard formulas and recalculates the moment you change a value, so the math is exact for the inputs you enter. Treat the result as a reliable planning estimate; for decisions with legal or tax consequences, confirm the figures with a qualified professional.
Yes. The calculator is mobile-friendly and works on any phone, tablet, or computer — there is no app to install and nothing to save.
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Last reviewed: September 2026. Free to use, no signup — Sales Tax Calculator by ToolWise Digital.
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