Why does this calculator not know my local rate?

Combined sales tax rates change frequently and can differ between neighbouring addresses in the same city. Rather than publish a rate table that quietly goes stale, this calculator uses the rate you supply from your receipt or your state revenue department.

What makes up a combined sales tax rate?

A state rate, often a county rate, sometimes a city rate, and in many areas a special district rate funding transit, stadiums, or similar. They are added together and applied as one rate at the register.

Sales Tax Calculator

Q: How do I remove sales tax from a total?

Divide the total by one plus the rate. A 107 dollar total at a 7 percent rate came from a 100 dollar pre-tax price. Subtracting 7 percent of the total instead gives the wrong answer, because the rate was applied to the smaller pre-tax figure.

What this calculator estimates

Three related calculations, depending on what you already know. Add tax to a listed price to find what you will actually pay. Remove tax from a total to find the pre-tax figure — useful for expense reports and bookkeeping. Or supply both figures and find the rate you were charged, which is the quickest way to check a receipt.

How to use it

Pick a mode. The form shows only the fields that mode needs.
Enter the price you have.
Enter the rate. If you know the single combined rate, put it in the top field. If you are building it up from state, county, city, and district components, leave that blank and fill in the parts.

How the calculation works

Adding tax is straightforward: the tax is the pre-tax price multiplied by the rate, and the total is the two added together.

Removing tax is where people go wrong. If a total of $107 includes 7% tax, the tax is not 7% of $107. The rate was applied to the smaller pre-tax figure, so you have to divide rather than subtract:

pre-tax price = total ÷ (1 + rate)

That gives $100, and the tax is the $7 remainder. Taking 7% of $107 would give $7.49 and leave you $0.49 out — small on one receipt, material across a year of expenses. This calculator derives the tax as the remainder rather than as a second multiplication, so the two parts always add back to your total exactly instead of differing by a cent.

Finding the rate simply divides the tax charged by the pre-tax price.

A worked example

A $249.99 item in a jurisdiction with a 6.25% state rate, a 0.75% county rate, and a 1.25% city rate. The combined rate is 8.25%, giving $20.62 of tax and a total of $270.61.

Run it in reverse: a $270.61 total at 8.25% divides back to $249.99, confirming the arithmetic in both directions.

Why there are no built-in rate tables

This is a deliberate choice rather than an omission. Combined sales tax rates in the United States change frequently — sometimes several times a year in one jurisdiction — and they vary by address, not just by city. Two shops on opposite sides of the same street can charge different rates if a special district boundary runs between them.

A built-in rate table would look authoritative and be quietly wrong within months. Asking for the rate from your receipt or your state's official lookup tool gives a result you can rely on. Every state revenue department publishes a current rate lookup, and the combined rate is printed on most receipts.

Important limitations

Exemptions are not applied. Many states exempt groceries, prescription drugs, or clothing, or tax them at a reduced rate. A single combined rate cannot capture that.
Tax holidays are not applied. Several states suspend sales tax on certain goods for a few days a year.
No nexus or remote seller rules. Which jurisdiction's rate applies to an online purchase depends on rules this calculator does not model.
Some items carry additional excise taxes — fuel, alcohol, tobacco, prepared food, hotel stays — that sit outside the general sales tax rate.

Frequently asked questions

How do I remove sales tax from a total?

Divide by one plus the rate, not by subtracting the rate from the total. Use the "Remove tax" mode above and it handles it correctly.

Why does the calculator not know my local rate?

Because combined rates change often and vary street by street. Publishing a table that goes stale would be worse than asking you for a figure you can read straight off a receipt.

What makes up a combined rate?

A state rate, usually a county rate, often a city rate, and in many areas a special district rate funding transit or similar local projects. They are summed and applied as one rate at the register.

Which states have no sales tax?

Alaska, Delaware, Montana, New Hampshire, and Oregon have no statewide sales tax, though some localities in Alaska levy their own. Enter a rate of zero for a state-level calculation in those states.

Is sales tax deductible on my federal return?

If you itemize, you can deduct either state and local income tax or state and local sales tax, but not both. Which one is better depends on your circumstances, and the deduction is subject to a cap.

Official sources

Federation of Tax Administrators — directory of state revenue departments and their rate lookup tools.
IRS Schedule A — the state and local tax deduction.