What this sales tax calculator does
This sales tax calculator handles the two real-world questions people actually ask: "what does this cost with tax?" and "how much of this total is tax?". The first is the everyday checkout maths; the second is what you need when you have a receipt or invoice with the tax already baked in and you want to know the pre-tax base. Both update live as you type, with a clear step-by-step breakdown beneath the result.
The formulas, plainly stated
To add tax to a pre-tax price:
Tax = Price × (Rate ÷ 100)Final = Price + Tax = Price × (1 + Rate ÷ 100)
To extract tax from a tax-inclusive total:
Pre-tax = Total ÷ (1 + Rate ÷ 100)Tax = Total − Pre-tax
The extract version trips people up: you cannot just multiply the total by the rate, because the rate was applied to the smaller pre-tax base, not the bigger total. Dividing by (1 + rate/100) reverses that step exactly.
US sales tax is a patchwork
Unlike most countries, the US doesn't have a single national sales tax. Each state sets its own rate, then counties, cities and special districts can add their own on top. The result is over 11,000 distinct combined rates. Five states (Alaska, Delaware, Montana, New Hampshire, Oregon) have no statewide sales tax at all, though Alaska allows local sales taxes. At the other end, combined rates in parts of Chicago, Los Angeles and Birmingham can exceed 10%. Check your state's department of revenue site for an exact, up-to-date rate.
What is and isn't taxed
Almost every US state taxes prepared food, restaurant meals, alcohol and tangible retail goods. Most exempt or reduce tax on unprepared groceries — buying chicken at the supermarket is usually tax-free, but a rotisserie chicken from the deli might not be. A handful of states exempt clothing entirely (Pennsylvania), or under a price threshold (Massachusetts, $175 per item). Many states have an annual "tax-free weekend" for back-to-school clothing or hurricane prep. Always check your receipt for the actual taxed line items.
Business uses
Small businesses use the "extract" mode constantly. If a client agrees to a $1,000 fixed fee that's tax-inclusive, you owe sales tax on that pre-tax base, not on the full $1,000. Same when reconciling a register where everything was rung up tax-included. For US online sellers, the 2018 Wayfair ruling expanded which states can require collection — most large marketplaces collect on your behalf, but if you sell on your own site, sales tax compliance gets real fast.
Use with the other tools
For income tax, use the federal income tax percentage calculator. For shopping discounts where you want sale price plus tax in one go, try the percent off calculator. For general percentage maths beyond tax, the percentage calculator covers every common variation.