Sales Tax Calculator
Sales Tax Calculator
Calculate a tax-inclusive price, reverse a total to find the pre-tax price, or derive the effective sales tax rate from a receipt.
Transaction inputs
Choose the value to calculate, then enter the other two values. The selected target updates automatically.
The selected field becomes a calculated, read-only value.
Enter the taxable price before sales tax.
Use the combined applicable state and local rate.
Calculated automatically from price and rate.
Live results
After-tax price
$106.50
After-tax price = before-tax price × (1 + tax rate).
Price breakdown
See how much of the final amount is the original price and how much is sales tax.
Composition of the amount paid
Sales tax adds $6.50 to the $100.00 pre-tax price.
Calculation detail
All rows use the same current-state model as the headline result, chart, and Excel export.
| Component | Amount | Share of final price | Calculation |
|---|
What this sales tax calculator estimates
This calculator connects three transaction values: the price before tax, the sales tax rate, and the final price after tax. Select which value you want to solve for and provide the other two. It is useful for adding tax to a listed price, removing included tax from a receipt total, or estimating the effective rate shown by a transaction.
The tool performs arithmetic only. It does not determine whether a product or service is taxable, which jurisdiction governs a sale, whether a buyer qualifies for an exemption, or whether a seller has a collection obligation. Those questions depend on current state and local rules, sourcing rules, product classifications, and the facts of the transaction.
How to use every input
Calculate
Choose After-tax price when you know the listed pre-tax amount and the applicable rate. Choose Before-tax price when a receipt or advertised amount already includes sales tax and you want to reverse it. Choose Sales tax rate when both the pre-tax and final prices are known. The selected target becomes read-only so the two source values remain unambiguous.
Before-tax price
This is the taxable base before sales tax is added. Enter a nonnegative dollar amount. A higher pre-tax price increases the tax amount proportionally when the rate stays constant. A common mistake is entering a total that already includes tax while also selecting After-tax price; for a tax-inclusive total, switch the calculation target to Before-tax price instead.
Sales tax rate
Enter the combined rate applicable to the transaction, expressed as a percentage. The combined rate may include state, county, city, district, or other local components. The correct rate can depend on the exact destination or origin address and on the product category. Because rates and boundaries change, verify the rate with the relevant state tax authority or a current address-level lookup rather than relying on an old receipt or a general ZIP-code average.
After-tax price
This is the amount paid after sales tax is added. When solving for the pre-tax price, the calculator divides the final amount by one plus the rate; it does not simply subtract the rate percentage from the total. When solving for the rate, the final price must be at least as large as the pre-tax price, and the pre-tax price must be greater than zero.
Understanding the results
Before-tax price is the taxable base. Sales tax amount is the dollar difference between the final and pre-tax prices. After-tax price is the total paid. Effective tax rate is the tax amount divided by the pre-tax price, which should match the entered rate except for small display-rounding effects.
The donut chart separates the final price into the original price and the tax portion. The percentages in the legend are shares of the final amount, not rates applied to the pre-tax base. For example, a 6.50% tax rate produces a tax share slightly below 6.50% of the final total because the denominator includes both the base and tax.
The detail table cross-checks the same model. The before-tax row shows the taxable base, the tax row shows the added amount, and the final row shows their sum. A zero tax rate produces a single, clearly labeled 100% pre-tax component rather than a decorative empty ring.
Formulas used
- Sales tax amount: before-tax price × tax rate ÷ 100.
- After-tax price: before-tax price × (1 + tax rate ÷ 100).
- Before-tax price: after-tax price ÷ (1 + tax rate ÷ 100).
- Sales tax rate: (after-tax price ÷ before-tax price − 1) × 100.
The reverse formula matters. Subtracting 6.5% from a tax-inclusive total does not correctly recover the base because the 6.5% rate was originally applied to the smaller pre-tax amount.
Rates, exemptions, and compliance
U.S. sales tax is generally administered by state and local jurisdictions rather than as one federal retail sales tax. The applicable rate and taxability can vary by address, item, buyer, and transaction type. Remote sellers may also need to consider economic nexus and marketplace-facilitator rules. The Streamlined Sales Tax Governing Board provides educational material for remote sellers, while the Federation of Tax Administrators maintains links to state tax agencies.
Sales tax paid during the year is a different topic from calculating tax on one purchase. Individuals considering an itemized federal deduction should review the IRS sales tax deduction guidance. Keep transaction records when they are needed for accounting, returns, exemptions, or deductions.
Common mistakes and practical checks
- Using a state base rate while ignoring local additions or special district rates.
- Applying a general rate to exempt, reduced-rate, or specially taxed goods and services.
- Subtracting a percentage directly from a tax-inclusive total instead of dividing by one plus the rate.
- Rounding intermediate values too early. This calculator retains full precision and rounds only for display and export.
- Assuming a calculated rate proves the correct legal rate. Receipt-level rounding, fees, discounts, mixed taxability, and multiple items can produce an apparent rate that needs further review.
To test a result, confirm that the before-tax price plus the tax amount equals the final price and that the tax amount divided by the pre-tax price equals the rate. Changing the price should change the tax dollars proportionally, while changing only the rate should leave the pre-tax base unchanged.