Sales Tax Calculator: How to Calculate Sales Tax Correctly Every Time

You're about to buy a $1,200 laptop, a $40,000 car, or $8,000 worth of materials for a construction project. You see the pre-tax price — but the final number at checkout is always higher. Sometimes significantly higher.

Sales tax is a consumption tax levied by state and local governments on the sale of goods and services. It's one of the most variable and confusing taxes in America because it differs not just by state but by county, city, and even the type of product being purchased.

The Sales Tax Formula (It Really Is This Simple)

Sales Tax Amount = Purchase Price × Tax Rate
Total Cost = Purchase Price + Sales Tax Amount

Or if you need to work backwards from a total that already includes tax:

Pre-Tax Price = Total Price ÷ (1 + Tax Rate)
Tax Amount = Total Price − Pre-Tax Price

Quick examples at typical rates:

US State Sales Tax Rate Overview

Five states charge no sales tax at all: Alaska, Delaware, Montana, New Hampshire, and Oregon. For residents of these states, the sticker price is the final price.

For everyone else, the combined rate is state + county + city:

Note that in Tennessee and Louisiana, combined rates regularly exceed 10% in major metro areas — effectively adding $100 fee for every $1,000 spent.

Sales Tax for Large Purchases: Where It Really Matters

For small purchases, tax is barely noticeable. But for large transactions, accurate calculation matters:

Vehicle purchases: On a $35,000 car in a high-tax state like California (8.82% average combined rate), you owe $3,087 in sales tax — more than many people's first or last car payment. Knowing this upfront prevents budget surprises.

Home improvement projects: Materials for a $25,000 kitchen remodel taxed at 9% = $2,250 in sales tax you need to factor into your project budget.

Business equipment: When purchasing equipment, a business may qualify for sales-tax exemption if the equipment is used in production. Always verify your state's exemptions before paying tax on a large B2B purchase.

For Business Owners: Collecting and Remitting Sales Tax

If you sell goods or services, you're responsible for:

1. Determining nexus — Do you have physical presence, employees, or sufficient sales volume in a state? If so, you're required to collect that state's sales tax.
2. Charging the correct rate — Use the destination address (where the buyer receives the goods) to determine the applicable rate. This is called "destination-based sourcing."
3. Remitting collected taxes — Sales tax is collected on behalf of the government. Keeping it is a serious offense. Remittance schedules are usually monthly or quarterly.

Since the 2018 South Dakota v. Wayfair Supreme Court ruling, economic nexus means even remote sellers with no physical presence in a state may be required to collect sales tax once they reach a certain sales volume threshold (usually $100,000 in annual sales or 200 transactions in that state).

Use our Sales Tax Calculator to quickly calculate tax on any purchase — including multi-item orders and determining the pre-tax price from a tax-inclusive total.

Frequently Asked Questions

Is sales tax deductible on federal taxes? If you itemize deductions, you can deduct either state income tax OR state sales tax — not both. For residents of no-income-tax states (Texas, Florida, etc.), the sales tax deduction can be valuable. The IRS provides an optional Sales Tax Deduction Calculator in Publication 600.

Do online sellers charge sales tax? After the Wayfair ruling, most major online retailers (Amazon, Walmart, Etsy, etc.) collect and remit sales tax in all states with a sales tax. Small sellers may still be under the economic nexus thresholds in some states — but as your business grows, you'll trigger collection obligations in more states.