ReckonBoxHow the sales tax calculator works
Sales tax is the price times the combined sales tax rate for wherever the sale happens, so a $100 purchase at a 9.03% rate costs $9.03 in tax and $109.03 in total. Pick a direction: add tax to a price, or work the pre-tax price back out of a total you already paid. Choose a state to pull its average combined rate, or type in the exact rate if you know it.
The reverse direction is the one most calculators leave out, and it is the one you reach for at the register when only the tax-inclusive total is printed.
The two formulas
Forward, to add tax: Tax = Price x Rate, and Total = Price + Tax. At California's 9.03% combined rate, a $100 item is $9.03 of tax and $109.03 out the door.
Reverse, to back the tax out: Price before tax = Total / (1 + Rate). The rate goes in as a decimal, so 7.25% is 1.0725. An $858 credit card charge at 7.25% works back to $800 before tax and $58 of tax. The mental shortcut is to divide by one plus the rate: divide by 1.0725 for 7.25%, or by 1.06 for 6%.
Combined rates: state plus local
The rate you actually pay is a state base rate plus whatever local rate the county, city, or district adds on top. Thirty-eight states allow local sales taxes, so the combined rate is the one that matters at the register.
| State | State rate | Avg local | Combined |
|---|---|---|---|
| Louisiana | 5.00% | 5.13% | 10.13% |
| California | 7.25% | 1.78% | 9.03% |
| New York | 4.00% | 4.54% | 8.54% |
| Texas | 6.25% | 1.95% | 8.20% |
| Florida | 6.00% | 0.98% | 6.98% |
Louisiana tops the list at 10.13% combined, and the population-weighted national average is 7.53%. Five states levy no state sales tax at all: Delaware, Montana, New Hampshire, and Oregon collect nothing, while Alaska has no state rate but still lets towns add their own, averaging about 1.82%. These figures are the Tax Foundation's state averages as of 1 July 2026.
What a state average does not tell you
A state average is a fair estimate and a poor promise. Local rates change from one jurisdiction to the next, so two addresses a mile apart, or even two sides of the same ZIP code, can pay different rates. Avalara, whose whole business is pricing this correctly, warns that leaning on a ZIP code is not a reliable way to rate a sale.
So treat the combined figure here as a planning number. For an exact, address-level rate, check your state revenue department or a paid rooftop-lookup service, and if you already know your rate, enter it directly. This tool estimates the tax on a purchase, which is a different job from the IRS Sales Tax Deduction Calculator that works out what you can deduct on a federal return. It is an estimate for planning, not tax advice.
Frequently asked questions
How do I calculate sales tax on a purchase? Multiply the pre-tax price by the combined sales tax rate for the location. On a $100 purchase at a 9.03% combined rate, the tax is $9.03 and the total is $109.03. The combined rate is the state rate plus the local rate where the sale happens.
How do I find the price before tax from a total? Divide the tax-inclusive total by one plus the rate written as a decimal. A $858 total at a 7.25% rate is $858 divided by 1.0725, which is $800 before tax and $58 of tax. Switch this tool to reverse mode and it does that for you.
What is the combined sales tax rate, and why does it vary by state? The combined rate is the state sales tax plus the average local sales tax that counties and cities add on top. It runs from 0% in the no-tax states to about 10.13% in Louisiana, because 38 states let local governments levy their own sales tax. The rates here are population-weighted state averages from the Tax Foundation, as of 1 July 2026.
Which states have no sales tax? Five states levy no statewide sales tax. Delaware, Montana, New Hampshire, and Oregon collect none at all, while Alaska has no state rate but still lets local governments charge one, so its average is about 1.82%. Every other state charges a state rate, and most add local tax too.
Is the state-average rate exact for my address? No, treat it as an estimate. Local rates can differ within a single county or even a ZIP code, so two nearby addresses can pay different rates. For an exact, address-level rate, check your state revenue department or a paid address-lookup service. You can also switch this tool to a rate you enter if you already know the exact one.
Is this the same as the IRS sales tax deduction calculator? No. This tool figures the tax you pay at checkout on a purchase. The IRS Sales Tax Deduction Calculator estimates how much sales tax you can deduct on a federal income tax return if you itemize and deduct sales tax instead of state income tax. They answer different questions.