Sales Tax Calculator
Add sales tax to a price or reverse it out of a total. Enter an amount and a tax rate to see the tax and final total instantly.
Add tax — or work it backward
Most sales tax calculators only add tax to a price. This one goes both ways. Leave the box unchecked to add tax on top of a pre-tax amount, or check it to reverse the tax out of a total that already includes it — handy for figuring out how much of a receipt was actually tax, or backing into a pre-tax price for bookkeeping.
Enter the amount and your combined tax rate and you'll see the pre-tax figure, the tax amount, and the final total together. It's a quick way to check invoices, quotes, and expenses without a spreadsheet.
How it's calculated
Adding tax: tax = amount × rate ÷ 100, total = amount + tax. Removing tax: pre-tax = total ÷ (1 + rate ÷ 100), and tax = total − pre-tax. Everything is computed live in your browser.
Frequently Asked Questions
How is sales tax calculated?
Multiply the pre-tax amount by the tax rate as a decimal. For a $100 purchase at 8.25%, the tax is 100 × 0.0825 = $8.25, for a total of $108.25.
Can this remove tax from a total (reverse sales tax)?
Yes. Switch to “Total includes tax” and the calculator works backward to show the original pre-tax amount and how much of the total was tax.
What sales tax rate should I use?
Use the combined state and local rate for the buyer’s location. US rates commonly range from about 0% to over 10%. Check your local tax authority for the exact figure.
Is this calculator free and private?
Yes — it runs entirely in your browser with no sign-up, and nothing you enter is uploaded.
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