Adding tax and backing tax out of a total
To add sales tax, multiply the pre-tax price by the tax rate expressed as a decimal, then add that tax to the original price. To remove tax from a tax-inclusive total, divide the total by 1 + tax rate to recover the pre-tax price; the difference is the tax amount.
Worked example
For a $100 item taxed at 8.25%, tax is $8.25 and the total is $108.25. If $108.25 is already the tax-inclusive total, dividing by 1.0825 returns a $100 pre-tax price, subject to rounding.
Actual tax treatment depends on location, product type, exemptions, and the seller’s rules. This calculator applies one rate to the entered amount; it does not determine which rate legally applies, calculate multiple jurisdiction layers, or account for line-item rounding. Confirm the rate and rules for the purchase location.
Tips for accurate results
Enter the pre-tax price and the combined rate for your location, including state and local portions. To go from a tax-inclusive total back to the pre-tax price, divide by one plus the rate: $107 at 7 percent tax is $100 before tax.
Common mistakes and limits
Rates vary by location, and some items, such as certain groceries, clothing, or medicine, may be taxed differently or exempt. Stores may round tax per item or on the total, producing differences of a cent or two. Check your local tax authority for official rates.
Learn more: Percentages in everyday life.