Sales Tax Calculator
Free sales tax calculator. Add tax to a price or back it out of a total. US state sales tax rates built in. No signup.
What a sales tax calculator does
Sales tax is a percentage added to the price of most goods at the point of sale, collected by the seller and passed to the state. This calculator does the two jobs people actually need: add tax to a subtotal to get the final price, and reverse tax out of a total when all you have is the amount you paid. It carries each US state’s base rate and lets you override it with a custom rate for local add-ons.
How the calculator works
Both directions use the same rate, applied differently:
- Add tax: tax = subtotal × rate; total = subtotal + tax.
- Reverse tax: subtotal = total ÷ (1 + rate); tax = total − subtotal.
- If the custom rate field is blank, the selected state’s base rate is used. Enter a number there and it overrides the state.
A worked example
A $100 purchase in California (7.25% base state rate):
| Mode | Input | Calculation | Result |
|---|---|---|---|
| Add tax | Subtotal $100 | Tax = 100 × 0.0725 = $7.25 | Total $107.25 |
| Reverse tax | Total $100 | Subtotal = 100 ÷ 1.0725 = $93.24 | Tax $6.76 |
Notice the two tax figures are not symmetrical: adding 7.25% to $100 gives $7.25 tax, but a $100 total only contains $6.76 of tax, because the tax was charged on the smaller pre-tax amount. Reversing by multiplying the total by 0.0725 would overstate the tax — that is the most common sales-tax error.
Selected state base rates
| State | Base rate | State | Base rate |
|---|---|---|---|
| California | 7.25% | Nevada | 6.85% |
| Texas | 6.25% | Tennessee | 7.00% |
| New York | 4.00% | Washington | 6.50% |
| Florida | 6.00% | Colorado | 2.90% |
| Illinois | 6.25% | Oregon, Montana, New Hampshire, Delaware, Alaska | 0.00% |
These are state-level rates only. Counties and cities add their own, typically 0–5% on top, so the rate that applies at the register is often higher than the state base.
Common mistakes
- Removing tax by multiplying. To strip tax from a total you divide by (1 + rate), you do not multiply by the rate.
- Using the state rate when a local rate applies. In many states the combined county and city rate is the one charged, and it can be several points higher.
- Forgetting tax-exempt items. Many states exempt groceries, prescription medicine, or clothing up to a threshold, so a uniform rate over the whole basket overstates the tax.
- Assuming the rate is the same everywhere. Sales tax varies by state, county, and sometimes city; even a single retailer can charge different rates at two nearby branches.
Frequently asked questions
Why is the tax on my receipt higher than the state rate?
Because local authorities add to it. The state rate is only the floor; counties, cities, and special districts layer on top. To match a receipt exactly, enter the combined rate you were charged in the custom rate field.
Which states have no sales tax?
Five have no statewide sales tax: Alaska, Delaware, Montana, New Hampshire, and Oregon. Alaska and a few others still allow local sales taxes, so an individual city may charge one even though the state does not.
How do I work out the tax from a total I already paid?
Switch to the reverse mode and enter the total. The tool divides by one plus the rate, then shows the pre-tax subtotal and the tax separately. This is the correct approach when tax is already baked into the number you have.
Do online purchases use the same rate?
Generally the rate is based on where the buyer receives the goods, so an online order is usually taxed at your local rate rather than the seller’s. Marketplace and small-seller rules can complicate this, but the destination rate is the usual starting point.
Sales tax is only one line on a bill. If you are building a quote or invoice, the invoice generator applies a tax rate across multiple line items, and a percentage calculator is handy for checking discounts or margin alongside it.