Use this free sales tax calculator to add a known percentage to a price or work backwards from a tax-inclusive total. Choose whether your input is before or after tax, enter the price and provide the percentage rate. The tool separates the pre-tax price, the tax amount and the final tax-inclusive price. It can demonstrate the arithmetic of US sales tax, value-added tax (VAT), or another single percentage-based tax, but it does not automatically determine the applicable rate or whether a transaction is taxable.
## How to add sales tax. Convert the tax rate from a percentage to a decimal, then multiply the pre-tax price by (1 + rate). For example, if an item costs $100 before tax and the applicable rate is 8%, the tax is $100 × 0.08 = $8 and the total is $108. The calculator shows the rate you entered; it does not infer it from your location or the product category.
## How to remove included tax. When the total already includes a percentage-based tax, divide the tax-inclusive price by (1 + rate). With $108 including tax at 8%, the pre-tax value is $108 ÷ 1.08 = $100, and the included tax is $8. Subtracting 8% directly from $108 would incorrectly give $99.36 because the 8% rate applies to the tax-exclusive base, not the tax-inclusive total.
## Sales tax versus value-added tax. Mathematically, both can be calculated using the add-tax and extract-tax formulas for a single tax rate. Legally, the way tax applies depends on country, region, product, registration status, exemptions and other factors. This tool does not perform jurisdiction-specific sales-tax compliance, issue invoices or verify current rates. Do not assume that a tax rate shown in a receipt applies to every item or transaction.
Sales tax addition and reverse tax extraction
Price with tax = Before-tax price × (1 + Tax rate % ÷ 100)
Before-tax price = Price with tax ÷ (1 + Tax rate % ÷ 100)
Tax amount = Price with tax − Before-tax price
The percentage must be entered manually, be nonnegative and at most 100%. A single rate is assumed. Display amounts are rounded to cents; actual jurisdictional compliance and invoice rounding are not provided.
A product sells for $100 before tax, and you enter a hypothetical 8% tax rate.
Result: Price before tax = $100; sales tax = $8; total including tax = $108.
Multiply the pre-tax price by the tax rate as a decimal, then add that amount. At 8%, a $100 price has $8 tax and $108 total.
Divide the inclusive total by (1 + tax rate as a decimal). For $108 including 8% tax, divide by 1.08 to get $100 before tax.
The tax percentage applies to the before-tax base. Subtracting 8% of $108 would return $99.36, which is not the $100 tax-exclusive value.
No. It uses only the rate you enter. Actual tax rates and exemptions vary by location, item and transaction.
It can perform the arithmetic for a single percentage tax such as VAT. Enter the applicable rate yourself and select the extract-tax mode.
Some systems round each line item while others calculate and round the total. Tax laws may prescribe a method. This calculator displays a simple two-decimal approximation.
No tax is added or extracted; the before-tax and inclusive totals are equal.