Sales Tax Calculator — Add Tax or Extract It from a Total

Forward and backward

Forward is familiar: $49.99 at a combined 8.25% rate adds $4.12 of tax for a $54.11 total. Backward is the one people get wrong: a $100.00 receipt total at 8.25% contains $7.62 of tax — not $8.25 — because the tax was charged on the $92.38 pre-tax price, not on the total. Expense reports, budgeting, and VAT-inclusive price tags all need the backward direction. Every figure is computed by the same tested engine as the calculator above.

One purchase, many rates

US sales tax is a patchwork: the state base rate, county and city additions, and special district levies stack into the combined rate on your receipt — which is why the same purchase can be taxed differently across a county line. When precision matters, read the combined rate off a recent local receipt rather than assuming the state rate alone.

Whose rate applies? Origin vs. destination sourcing

When a seller in one town ships to a buyer in another, one question decides the rate: which location's combined rate governs? Tax law calls this sourcing, and for sales that stay inside one state, states answer it two ways. In an origin-based state, in-state orders are taxed at the rate in effect at the seller's place of business — every order you ship within the state carries the same combined rate, which makes a small seller's bookkeeping close to trivial. In a destination-based state, the rate is the one in effect where the buyer takes delivery — so a seller shipping statewide needs the correct rate per delivery address, which is why destination states typically publish address-level lookup tools and rate databases.

As of this writing, Ohio sources most in-state sales by Ohio vendors to the vendor's location (Ohio R.C. 5739.033), as does Tennessee (Tennessee DOR, SUT-29). Washington (Washington DOR) and Colorado (Colorado DOR) source to the delivery location instead. Don't generalize from these four: a few states blend the two models, and states rewrite their sourcing rules — Colorado's full transition to destination sourcing took effect in 2022 — so confirm your own state's current model with its revenue department before building a billing process around it. And once an order crosses state lines, sourcing is almost always destination: if you're required to collect for another state, that state's rules and rates govern.

The stakes are just arithmetic, which the calculator makes concrete. Take a $250.00 order under two illustrative combined rates: at 7% the tax is $17.50; at 9.25% it is $23.13 — a $5.63 difference on a single order, decided entirely by which address the sourcing rule points at.

Sales tax vs. use tax

Sales tax has a quieter twin. Every state that levies a sales tax also levies a use tax — a tax at the same rate, owed by the buyer, on taxable goods used in the state when the seller didn't collect sales tax at purchase. It exists to close the obvious loophole: without it, buying from an out-of-state seller who isn't required to collect would be a permanent discount, and in-state merchants would be undercut by their own state's tax. Classic triggers include an untaxed purchase from an out-of-state or online seller, goods bought tax-free for resale and then used by the business itself, and items brought into the state after being bought somewhere with a lower rate (many states credit the tax already paid elsewhere against what's owed).

Suppose you buy $1,200.00 of equipment and the seller, not being required to collect in your state, charges no tax. If your combined rate is 8.25%, you owe $99.00 of use tax directly to your state — states typically provide a line on the income-tax return or a separate form for it. Enter the price and your rate in "add" mode above and the tax figure is your use-tax amount. Compliance among individual consumers is famously low, but the obligation is real, and for businesses it's a routine audit item.

Marketplace facilitator laws, in brief

If you sell through a large online marketplace, much of this may be handled above your head. After the Supreme Court's South Dakota v. Wayfair decision (2018) let states require out-of-state sellers to collect based on economic activity rather than physical presence, states broadly adopted marketplace facilitator laws: when a third-party sale happens through a marketplace platform, the law makes the platform — not the individual seller — responsible for calculating, collecting, and remitting the sales tax on that sale. For a small seller this cuts both ways: marketplace orders largely take care of themselves, but sales through your own website or invoices remain your responsibility, and some states still expect registration or reporting from marketplace sellers. The thresholds and seller obligations differ by state — the state revenue department's marketplace-seller page is the authoritative version.

What's commonly exempt — and why the rate here is yours to enter

Not everything in a shopping cart is taxed, and not everything taxed is taxed alike. Prescription drugs are exempt in nearly every state with a sales tax. Unprepared groceries vary far more — depending on the state they may be fully taxed, taxed at a reduced rate, exempt from the state rate but not local rates, or exempt entirely — while prepared food, lodging, and rental cars often carry special higher rates on top of the ordinary combined rate. Some states exempt clothing under a threshold; some hold sales-tax holidays that suspend tax on back-to-school or emergency-supply categories for a weekend. All of this is state-specific and changes legislatively, so treat category rules as a question for your state's revenue department, not a rule of thumb.

This patchwork is exactly why the calculator asks for your rate instead of guessing it: statutory rates change mid-year, local add-ons stack differently at every address, and the category of the item can change the rate on a single receipt line. Verify the rate that applies to your purchase — a recent local receipt or your state's official rate lookup — and the math above will be exact for that rate.

Frequently asked questions

What sales-tax rate should I enter?

Your combined state + local rate — in most of the US the state sets a base rate and counties/cities add to it, with combined rates commonly ranging from 0% (five states have no statewide sales tax, though some of them — like Alaska — allow local ones) to around 10%+. Your receipt, your city’s finance site, or your state revenue department will show the exact combined rate for a location.

How does the reverse mode work?

Dividing, not subtracting: a total that already includes r% tax equals the pre-tax price × (1 + r/100), so the pre-tax price is total ÷ (1 + r/100). Subtracting r% of the total instead is a common error that overstates the tax — on a $100 total at 8.25%, the tax inside is $7.62, not $8.25.

Is everything taxed at the same rate?

No — many states exempt or reduce rates on groceries, prescription drugs, or clothing, and some levy special higher rates on prepared food, lodging, or rental cars. This calculator applies one flat rate to one amount; itemize separately when categories differ.

Does this handle VAT?

Mechanically yes — VAT-inclusive pricing works exactly like the reverse mode, and many countries quote prices with VAT included. Enter the VAT rate and the tax-inclusive price in extract mode to see the tax embedded in a price.

An online seller didn’t charge me sales tax — do I owe anything?

Possibly. States that levy sales tax also levy a companion use tax at the same rate: when a seller doesn’t collect on a taxable purchase you use in your state, the tax obligation shifts to you as the buyer. States typically provide a line on the income-tax return or a separate form for reporting it. Your state revenue department’s use-tax page explains what qualifies and how to report.

I sell online — do I charge my local rate or the buyer’s?

It depends on the state’s sourcing rules. For orders shipped across state lines where you’re required to collect, the destination state’s rules and rates almost always govern. For orders inside your own state, origin-based states apply the rate at your business location while destination-based states apply the rate at the delivery address — and a few blend the two. Confirm your state’s model with its revenue department before building a process around it.

Why doesn’t the calculator look up my rate automatically?

Because a stale lookup is worse than none. Thousands of overlapping state, county, city, and district rates change throughout the year, and category rules (groceries, prepared food, clothing) shift the effective rate per item. Rather than risk quoting an outdated figure, this tool takes the rate you verified — from a recent receipt or your state revenue department’s official lookup — and does the arithmetic exactly.

Not tax advice: rates and taxability vary by jurisdiction and product category — confirm the applicable rate with your state or local revenue authority. Values are processed locally in your browser and never transmitted. See the methodology page.