🧾 Sales Tax Calculator: Add or Remove Sales Tax by State

Sales tax calculator by state: enter your numbers

Pick a state so the result shows your jurisdiction, then type the combined sales tax rate you confirmed for your city and county. If you do not know it, check your state revenue department's rate page before relying on the number.

How to use this sales tax calculator

1. Choose the mode. Use "Add sales tax" when you know the pre-tax price. Use the reverse mode when the number in your hand is the tax-inclusive total.
2. Select your state. The state is used for the jurisdiction note shown with the result. It never fills in a rate for you, because no state rate was verified.
3. Enter the combined sales tax rate. Type the rate you confirmed for your location, or add your state, county, city and district lines and press "Apply parts to combined rate".
4. Enter price, quantity and any pre-tax discount. Add the shipping charge and tell the calculator whether your state taxes shipping. If you are not sure, pick "Unknown" and you will get both outcomes.
5. Pick the rounding convention. The default rounds the tax once per transaction, which is the common receipt pattern. Choose per-line rounding if you want each unit rounded separately.
6. Read the breakdown. The result shows the taxable base, the tax, the total, the effective rate, the substituted formula, and the status chip that tells you how strong the result is.

Use the Copy result button to paste the breakdown into a message or spreadsheet, or use Print view for a clean paper copy. Reset clears every field back to the example values.

How to calculate sales tax

Calculating sales tax takes three numbers: the taxable base, the combined rate, and your rounding choice. The taxable base is what you actually multiply — goods subtotal minus any pre-tax discount, plus shipping only if your state taxes it. Multiply the base by the rate, round once, and you have the tax.

Why the rate is a local number, not a national one

There is no federal sales tax in the United States. States impose a statewide rate, and counties, cities and special districts often add their own on top. The sum is the combined sales tax rate that applies at a given address, which is why two stores a few miles apart can charge different tax. Rate levels, the taxability of groceries, clothing, shipping, digital goods and services, and even where a remote seller must collect all vary by state. This calculator does the arithmetic; your state revenue department decides the rules.

How to calculate sales tax backwards

When a receipt shows only the total, divide that total by one plus the rate expressed as a decimal. A $217.75 total at 8.875% becomes 217.75 ÷ 1.08875 = $200.00, and the tax is the difference, $17.75. That is the whole trick the reverse sales tax calculator performs, and it is exact as long as the rate you enter is the rate that was charged.

Worked examples

Every example below uses hypothetical rates that are arithmetic inputs, not the rate of any real jurisdiction. The amounts were computed with exact decimal arithmetic on 2026-10-18 and re-checked against the calculator engine.

Try any of these in the form above: set the mode, type the rate, and the breakdown reproduces these numbers exactly.

Add tax versus remove tax, and rounding choices

Visual guide to the calculation

Common mistakes when you calculate sales tax

• Applying one state's rate to another. A rate seen in a neighboring state, a news article or an old receipt says nothing about your address. Confirm the combined rate for the location that matters.
• Treating a state base rate as the whole rate. The statewide portion is usually only part of the combined rate; county, city and district layers often add on top.
• Taxing shipping by default. Whether delivery charges are taxed depends on the state and sometimes on how the charge is shown on the invoice. Use the shipping choice and compare both outcomes when unsure.
• Rounding per item when the receipt rounds once. On small lines the two conventions can differ by a cent; the examples table shows the $0.99 case.
• Mistaking an estimate for a filing number. This tool computes arithmetic; it does not file, collect or remit tax, and it does not replace a state revenue department rate lookup.
• Forgetting the discount is pre-tax. A discount taken after tax does not reduce the taxable base the same way; enter the discount that applies before tax.

Sales tax calculator FAQ

Glossary

Combined sales tax rate

The sum of the state, county, city and special district rates that apply at one location. This is the single percentage you enter in the calculator, and it is the number that decides your tax amount.

Taxable base

The amount the rate is applied to: goods subtotal minus any pre-tax discount, plus shipping only when your state taxes it.

Pre-tax price

The price before sales tax is added; in reverse mode it is the total divided by one plus the rate.

Sourcing (origin vs destination)

Which address decides the rate on a shipped order — the seller's location or the buyer's. States differ, and this choice is not modeled here.

Economic nexus

The level of sales into a state that can oblige an out-of-state seller to collect that state's tax, a standard reshaped by South Dakota v. Wayfair, Inc. (2018).

Use tax

The tax owed to your state when a purchase was made without sales tax being collected, such as on an out-of-state order.

Related calculators

Other tools on Varnda that pair well with this one when you are budgeting a purchase or checking a bill:

• Mortgage Calculator — estimate a monthly payment including taxes, insurance and PMI.
• Paycheck Calculator — estimate take-home pay after deductions.
• Credit Card Payoff Calculator — see how long a balance takes to clear.
• Personal Loan Calculator — monthly payment, interest and total cost.

Official references and last-checked dates

Nothing in this list was opened, downloaded or reviewed. They are the official starting points you should check yourself before relying on any rate or rule.

• Streamlined Sales Tax Governing Board — https://www.streamlinedsalestax.org/.
• Federation of Tax Administrators (directory of state tax agencies) — https://www.taxadmin.org/.
• USAGov directory of state tax agencies — https://www.usa.gov/state-tax-agencies.
• Your state's department of revenue or taxation sales tax page.

Byline: Varnda Editorial Team. Corrections: use the contact or correction channel published on the Varnda site; no email address or form is invented on this page.

Changelog

• 2026-10-18 — Initial build: add and reverse engine, rate builder, shipping taxability choice, per-transaction and per-line rounding, receipt breakdown, examples, FAQ. All regulated numbers (rates) kept as editable inputs.

Limitations, exclusions and assumptions

• Rate accuracy is yours. The result is only as correct as the rate entered; rates change and vary by state, county, city and special district.
• Rule status.
• Shipping unknown. If you select "Unknown", the result returns estimate with limitations and shows both the taxed and untaxed shipping outcomes.
• Not represented: product taxability rules, exemptions and resale certificates, tax holidays, excise and lodging taxes, vehicle and real estate transactions, marketplace-facilitator and nexus questions, use tax filing, and tax on services.
• Rounding. Nearest cent, half up, once per transaction by default — a calculator convention, not a legal rule. A state bracket schedule may produce a different cent.
• No filing. This tool does not file, collect or remit tax and does not replace a state revenue department rate lookup.

Summary

A sales tax calculator earns its place by being transparent about arithmetic and honest about rates. This page adds sales tax to a price, removes sales tax from a total, shows the receipt-style breakdown and the formula with your own numbers, and labels every status: what is computed exactly, what is an estimate, and what is out of scope. What it will not do is invent your local rate. Confirm the combined sales tax rate for your location with your state revenue department, enter it above, and the math is exact to the cent.

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