The basic formula: multiply the price by the tax rate

To figure out sales tax, multiply the item's price by the tax rate in your area, then add that amount to the price. If an item costs $50 and your sales tax rate is 8%, you multiply $50 by 0.08 to get $4. The total you pay is $50 + $4 = $54.

The tax rate varies by location. Some states have no sales tax at all. Others charge between 4% and 10% depending on the state, and some cities or counties add their own local tax on top of the state rate. You can find your local rate by searching "[your city] sales tax rate" or checking your state's department of revenue website.

Most stores calculate this for you at checkout, so you see the final total on the receipt. But knowing how to do it yourself is useful when you are shopping online, comparing prices across states, or checking whether a receipt is correct.

Key Takeaways

  • Sales tax is calculated by multiplying the item price by the tax rate as a decimal (so 8% becomes 0.08).
  • Tax rates vary by state and sometimes by city or county, ranging from 0% to over 10%.
  • Most purchases are taxed, but groceries, prescription medications, and some clothing are often exempt depending on your state.
  • Online purchases may or may not be taxed depending on where the seller is located and where you live.

Converting a percentage to a decimal for the calculation

The percentage sign can be confusing when you are doing math. To convert a tax rate percentage into the decimal you need for multiplication, divide the percentage by 100 or straightforward move the decimal point two places to the left.

If your tax rate is 7%, that becomes 0.07. If it is 9.5%, that becomes 0.095. Once you have the decimal, multiply the item price by that number. A $100 purchase at 9.5% tax is $100 × 0.095 = $9.50 in tax, for a total of $109.50.

What items are usually exempt from sales tax

Not everything you buy is taxed. Most states exempt groceries and prescription medications from sales tax. Some states also exempt clothing, diapers, or medical equipment. The rules differ by state, so an item that is taxed in one state might not be in another.

Non-food items sold in a grocery store — like paper towels, cleaning supplies, or vitamins — are usually still taxed even though they are in a grocery store. The exemption typically applies only to food meant for eating. If you are unsure whether a specific item is taxed in your state, check your state's department of revenue website or ask the cashier.

How combined state and local tax rates work

Many places layer taxes on top of each other. You might have a state sales tax of 5% plus a city tax of 2%, for a combined rate of 7%. Some states also allow counties to add their own rate. When you search for your local tax rate, the number you find usually already includes all these layers combined.

If you are shopping near a state border or ordering from out of state, the tax rate that applies depends on where the item is being delivered or picked up, not where the seller is located. A purchase shipped to your home address is taxed at your home address rate. An item you pick up in a store is taxed at that store's location rate.

Calculating tax on multiple items or discounts

When you buy several items, you can calculate the tax two ways. You can add up all the prices first, then multiply the total by the tax rate. Or you can calculate tax on each item separately and add those taxes together. Both methods give the same answer.

If a store offers a discount, the tax is usually calculated on the discounted price, not the original price. So a $100 item with a 20% discount costs $80, and tax is calculated on $80. Some stores explore the discount after tax is added, which changes what you pay, so check your receipt if the math seems off.

Sales tax on online and mail orders

Whether you pay sales tax on an online purchase depends on two things: whether the seller has a physical location or employees in your state, and whether your state requires remote sellers to collect tax. Most large online retailers now collect sales tax on orders shipped to states where they have a presence, but smaller sellers may not.

If you buy from a seller outside your state and no tax is collected at checkout, you may owe "use tax" to your state — a tax on items you bought out of state and brought home. Most people do not pay this, and most states do not actively pursue it for individual purchases, but the tax technically exists. Check your state's rules if you regularly buy from out-of-state sellers.

Using a calculator or receipt to verify the math

If you want to check whether a store calculated tax correctly, use a basic calculator or your phone's calculator app. Multiply the subtotal (the price before tax) by the tax rate as a decimal. The result should match the tax amount shown on the receipt.

If the numbers do not match, the difference is usually small and caused by rounding — tax is rounded to the nearest cent. If the difference is more than a few cents, ask the cashier or check the receipt again. Stores sometimes explore different tax rates to different items if some are exempt, which can make the total tax look unexpected.

Frequently Asked Questions

Do I have to pay sales tax on everything I buy?

No. Groceries, prescription medications, and some other items are exempt in most states. Clothing is exempt in some states but taxed in others. Check your state's rules to know which items in your area are taxed.

Why is the total on my receipt different from what I calculated?

The most common reason is rounding. Tax is rounded to the nearest cent, so if your calculation gives $9.504, the store rounds it to $9.50. If the difference is more than a few cents, some items may be exempt from tax, or the store may have applied a discount you did not notice.

Do I pay sales tax when I order something online?

It depends on the seller and your state. Large retailers usually collect sales tax on orders shipped to your state. Smaller sellers may not. If no tax is collected, your state may require you to pay use tax, though enforcement varies.

What if I buy something in one state and take it to another?

You pay the sales tax rate of the state where you buy it, not where you live. Tax is based on the location of the sale, not where you live or where you use the item.