Sales Tax Calculator
Add sales tax to any price.
Details
Price after tax
$107.25
Includes $7.25 sales tax
This adds sales tax to a price, or works backwards from a total to find the pre-tax price and the tax inside it.
It handles combined state and local rates, which is what you actually pay at the register.
How sales tax is calculated
Sales tax is a percentage added to a purchase at the point of sale. In the US it is charged by states and by local jurisdictions, and there is no national rate.
The rate you actually pay is a combination: a state rate plus county, city and sometimes special district rates stacked on top. A 6.25% state rate can easily become 8.25% at the till, and the total can differ between two shops a few miles apart.
Two calculations matter. Forward: price × rate gives the tax. Backward: given a total that already includes tax, divide by 1 + rate to recover the price. Subtracting the percentage instead is the common mistake, and it gives the wrong answer.
Reversing means dividing, not subtracting. Taking 8.25% off $108.25 gives $99.32, which is $0.68 wrong, and the error grows with the amount.
What to enter
- Price
- The pre-tax amount. If you only have the total, use the reverse calculation instead.
- Sales tax rate
- Use the combined rate for the exact address, not just the state rate. Local additions are often the larger part of the difference.
- Direction
- Adding tax to a price, or extracting the tax already inside a total.
What this assumes
Rates are set locally and change. Confirm the current combined rate with your state's department of revenue if it matters.
Many states exempt or reduce tax on certain goods, most commonly groceries, prescription medicine and clothing.
How to calculate sales tax on a purchase
Multiply to add tax. Divide to take it out.
- rate
- The combined rate as a decimal, so 8.25% is 0.0825
- 1 + rate
- 1.0825 at 8.25%. Multiply going forward, divide coming back
Find the combined rate. State plus county plus city plus any special district. State revenue departments publish lookup tools by address.
Convert it to a decimal. Divide by 100. 8.25% becomes 0.0825.
Multiply to add tax. Price times the rate gives the tax; price times 1 + rate gives the total directly.
Divide to reverse it. Total divided by 1 + rate gives the pre-tax price. Subtract that from the total for the tax inside.
See a worked example: adding tax, then taking it back out
- Price
- $100
- Combined rate
- 8.25%
Tax: $100 × 0.0825 = $8.25. Total: $108.25.
Reversing: $108.25 ÷ 1.0825 = $100.00.
Doing it wrong: $108.25 − 8.25% = $99.32, which is $0.68 out.
On a $5,000 total the same error would be $31.44, which is why expense reports and invoices get this wrong so often.
$108.25 total, $8.25 of tax
Frequently asked questions
Divide the total by 1 plus the rate. At 8.25%, divide by 1.0825. A $108.25 total gives a $100.00 price.
Do not subtract the percentage from the total. The tax was calculated on the smaller pre-tax figure, so subtracting from the larger one always undershoots.
Because counties, cities and special districts add their own rates on top. The combined rate is what you pay, and it can vary between neighbouring towns.
In some states local additions are a couple of percentage points. Your state's department of revenue usually offers an address-level lookup for the exact combined rate.
Five states have no statewide sales tax: Alaska, Delaware, Montana, New Hampshire and Oregon.
Alaska is the exception worth knowing: it has no state rate but local jurisdictions can and do impose their own, so some Alaskan purchases are taxed.
No, and exemptions vary a lot by state. Groceries, prescription medicine and sometimes clothing are commonly exempt or reduced.
Services are treated inconsistently. Some states tax a wide range of services and others tax almost none, so the answer genuinely depends on where you are.
It is generally charged at the rate for your delivery address, not the seller's location, following the 2018 *South Dakota v. Wayfair* decision that let states tax remote sellers.
Most large retailers and marketplaces now collect it automatically. Where a seller does not, some states expect the buyer to report use tax instead.
Not quite. US sales tax is charged once, at the final sale to the consumer. VAT, used across Europe and much of the world, is collected at each stage of production with credits for tax already paid.
The other visible difference is display. US prices are usually shown before tax, while VAT is normally included in the advertised price.
Problems people actually run into
Subtracting the percentage to reverse a total
Taking 8.25% off a $108.25 total gives $99.32, not $100. The percentage was applied to the smaller number, so it cannot be removed from the larger one.
Always divide by 1 + rate. The error is small on a coffee and material on an invoice, and it is the single most common sales tax mistake.
Using the state rate instead of the combined rate
Budgeting a large purchase on the state rate alone understates the bill, sometimes by a couple of percent.
On a $30,000 car, the gap between a 6.25% state rate and an 8.25% combined rate is $600. Look up the rate for the actual address before relying on the figure.
Results are estimates for general information only and are not professional financial, medical, or legal advice. Read our full disclaimer.
Last updated: September 4, 2026