Sales Tax Calculator (US)
Add sales tax to a price, or work out the pre-tax price and tax amount from a total that already includes tax — using average combined state and local rates for all 50 states plus DC, or your own custom rate.
Average combined state + local rate (Tax Foundation)
How sales tax is calculated
Adding tax multiplies the pre-tax price by (1 + tax rate). Removing tax divides the tax-included total by the same factor to find the pre-tax price.
For example, a $100 item in California (average combined rate 8.85%) costs $108.85 after tax — a tax amount of $8.85.
Frequently asked questions
How is US sales tax calculated?
Sales tax is a percentage added to the price of most goods and services at the point of sale. The combined rate is usually the state rate plus any city, county, or special district rate that applies where the purchase is made — which is why rates vary so much by location.
Which states have no sales tax?
Alaska, Delaware, Montana, New Hampshire, and Oregon have no statewide sales tax. Alaska still allows local sales taxes in some areas, so the effective rate there isn't always zero.
Why does this calculator use an 'average' rate per state?
Sales tax rates vary by city and county within most states, sometimes significantly. This calculator uses the Tax Foundation's population-weighted average combined state and local rate for each state as a reasonable estimate — switch to 'Custom rate' if you know your exact local rate.
How do I back out sales tax from a total that already includes it?
Switch to 'Remove tax from price' and enter the total you paid. The calculator divides by (1 + tax rate) to find the pre-tax price, then the difference is the tax amount — useful for expense reports or checking a receipt.