Free Sales Tax Calculator
Calculate sales tax instantly. Add tax to a price or calculate the tax included in a total.
Start with a price that does not include tax. Switching modes keeps your entries.
US dollars, up to 2 decimal places. Pasted values such as $1,234.56 are accepted.
Enter the applicable combined rate, including local taxes. The placeholder is an example, not a location rate.
Your calculation
Enter a valid amount and tax rate to see your results.
- Price before tax
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- Sales tax percentage
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- Sales tax amount
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- Total including tax
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All amounts are in USD. Calculations stay in this page and update as you type.
Use the combined rate that applies to your purchase. This tool calculates amounts from your inputs; it does not determine tax rates, exemptions, or a seller’s legal obligations.
How to Calculate Sales Tax
To calculate sales tax on a purchase, multiply its taxable price by the percentage rate expressed as a decimal. Add that tax to the original price to get the total.
Sales tax = Price × (Tax rate ÷ 100)
Total = Price + Sales tax
For a $200 price at an illustrative 7.5% rate: $200 × 0.075 = $15 in tax. The final total is $200 + $15 = $215. Enter the percentage as 7.5 in the calculator.
How to Calculate Sales Tax Backwards
Use the reverse sales tax calculator when the amount you have already includes tax. Divide that total by 1 plus the decimal tax rate. Subtract the original price from the total to find the included tax.
Price before tax = Total ÷ (1 + Tax rate ÷ 100)
Sales tax = Total − Price before tax
For a $107.50 total at 7.5%: $107.50 ÷ 1.075 = $100 before tax. The tax included is $107.50 − $100 = $7.50. Subtracting 7.5% of the total would give a different, incorrect answer because the rate applies to the pre-tax price.
Sales Tax vs Total Price
The price before tax is the taxable amount you start with. The sales tax amount is the dollar charge calculated from the rate. The total price is the sum of those two amounts. For a basket containing exempt and taxable items, separate the taxable portion before using a single-rate calculation.
USD inputs accept up to two decimal places and rates accept up to six. In Add Tax mode, tax is rounded to the nearest cent, with exact half cents rounded up, then added to the price. In Reverse Tax mode, the pre-tax price is rounded the same way and tax is the remaining portion of your total. This keeps the displayed amounts consistent. Different line-by-line or jurisdiction-specific rounding rules can produce a different invoice result.
How US Sales Tax Rates Work
A combined sales tax rate can include state, county, city, and special district components. Exact rates depend on the jurisdiction and transaction. Product taxability, exemptions, sourcing rules, and the seller’s obligations also matter; some purchases may be exempt.
Use your state revenue department’s current guidance for the transaction date. The California tax-rate FAQ explains local district taxes and why ZIP codes do not always determine the correct rate. The Texas sales and use tax guidance includes an address-based rate locator and information about taxable services.
This calculator uses manual rate entry and does not supply state presets or automatic address lookups. A state-only reference would not necessarily include local taxes or establish whether your purchase is taxable.
Using Sales Tax on an Invoice
Before adding tax, identify the taxable charges and verify the applicable rate. Display the subtotal, tax rate, tax amount, and final total so the customer can understand what they owe.
Our free invoice generator supports a manually entered tax percentage and shows tax in the preview and downloaded PDF. It calculates tax on the discounted subtotal, so confirm that this treatment fits your invoice. Calculations here are separate and are not transferred automatically.
For the full document workflow, read how to create an invoice. For payment deadlines after the total is agreed, see our invoice payment terms guide.
Frequently Asked Questions
How do I calculate sales tax?
Multiply the taxable price by the tax rate divided by 100. For a $200 purchase at 7.5%, tax is $15 and the total is $215.
How do I calculate sales tax backwards?
Divide the tax-inclusive total by 1 plus the rate divided by 100. At 7.5%, $107.50 ÷ 1.075 gives a $100 pre-tax price. The remaining $7.50 is tax.
What is the formula for sales tax?
Sales tax = taxable price × (tax rate ÷ 100). Total price = price before tax + sales tax. This calculator assumes the full entered amount is subject to a single combined rate.
How do I calculate 8% sales tax?
Multiply the price by 0.08. For example, 8% of $50 is $4, making the final total $54. Enter 8 in the tax-rate field, rather than 0.08.
Is sales tax the same in every US state?
No. State systems differ, and county, city, and special district taxes can change the combined rate within a state. Some states have no statewide general sales tax, and local rules can still matter.
Does sales tax apply to services?
It depends on the service and jurisdiction. Some services are taxable and others are exempt. Check the relevant state revenue department's guidance before charging tax; this calculator does not determine taxability or your collection obligations.
Can I calculate sales tax using a ZIP code?
A ZIP code alone may cross tax jurisdiction boundaries and may not identify the exact combined rate. This calculator does not look up ZIP codes. Confirm the applicable rate using official guidance or an address-based state tool, then enter it manually.
How do I add sales tax to an invoice?
Confirm which charges are taxable and the applicable rate. Show the taxable price, tax amount, and total clearly. You can enter a tax percentage in our invoice generator, which calculates tax on the discounted subtotal. Check that this matches the transaction's tax treatment.