How the sales tax calculator works
Sales tax is a percentage added to the price of taxable goods and some services at checkout. In the U.S. it is set by states, and many counties and cities add their own rate on top, so the rate you pay depends on where you buy. This calculator works in both directions: it adds tax to a pre-tax price, or it removes tax from a total that already includes it.
The formula
Adding tax: tax = price × rate, and total = price × (1 + rate). Removing tax: pre-tax price = total ÷ (1 + rate), and tax = total − pre-tax price. A common mistake is to subtract the rate from the total directly; that removes too much, because the tax was calculated on the smaller pre-tax price.
Example
A $100 item at a 7.25% rate has $7.25 of tax, for a total of $107.25. Going the other way, a receipt total of $107.25 at 7.25% means the item cost exactly $100 before tax — not $99.47, which is what you would get by subtracting 7.25% of the total.
Finding your rate
Use the combined rate for your location, which is the state rate plus any county, city or special district rates. Your state department of revenue usually publishes a rate lookup by address. Five states — Alaska, Delaware, Montana, New Hampshire and Oregon — have no statewide sales tax, although many Alaska localities charge one. Groceries, clothing and medicine are taxed at reduced rates or exempt in many states.
Frequently asked questions
How do I calculate sales tax in my head?
Find 10% by moving the decimal, then adjust. For 7% of $50, 10% is $5, so 7% is $3.50.
Is sales tax charged on shipping?
It depends on the state. Some tax shipping charges when the item itself is taxable; others do not.
Do I pay sales tax on online purchases?
Usually yes. Most states require large online sellers to collect tax based on your shipping address.
What is use tax?
Use tax is owed by the buyer when sales tax was not collected on a taxable purchase used in their state.
Results are estimates for educational purposes only and are not financial, tax, legal or medical advice. See our disclaimer. Last reviewed 2026-10-22.