Free tool
Sales tax calculator
Enter an amount and a combined sales-tax rate. Switch modes to add tax to a net price or back tax out of a gross total.
- Pre-tax amount
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- Sales tax
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- Total
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Adding vs backing out sales tax
To add tax: tax = amount × rate; total = amount + tax. To back tax out of a total that already includes it: pre-tax = total ÷ (1 + rate), and tax = total − pre-tax. Reverse math matters when a receipt shows only the grand total or when you price items "tax included".
Frequently asked questions
How do I calculate sales tax?
Multiply the pre-tax amount by the combined sales-tax rate (state + county + city + special district). To find the pre-tax amount from a tax-inclusive total, divide the total by 1 + the rate.
What sales-tax rate should I use?
Use the combined rate for the location where the sale is taxed. In most US states that is the buyer’s location for shipped goods and the store location for in-person sales. Rates commonly range from about 4% to 10%+.
Does my POS calculate sales tax automatically?
Most modern POS systems apply tax rates and rules per item and per location, and many integrate address-based tax services. This calculator is for quick manual checks and reverse-tax math.
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