Sales Tax Calculator

How the Sales Tax Calculator Works

Our sales tax calculator helps you figure out the tax on any purchase in two ways. In "add tax" mode, you enter a pre-tax price and the calculator shows the tax and the total you'll pay. In "reverse" mode, you enter a total that already includes tax and the calculator works backward to find the original pre-tax amount and the tax portion. This is especially useful when you have a receipt showing only the total and you need to split out the tax for accounting or reimbursement.

Sales Tax Formula (Add Mode)

Tax = Amount × (Rate ÷ 100)    Total = Amount + Tax

For example, a $100 purchase at a 7% tax rate generates $7 in tax, for a total of $107. The effective rate — the tax as a share of the total — is 7% in this case, but it differs from the headline rate when you reverse the calculation.

Reverse Sales Tax Formula (Remove Tax)

Pre-Tax = Total ÷ (1 + Rate ÷ 100)    Tax = Total − Pre-Tax

For example, if you paid $107 total at a 7% tax rate, divide 107 by 1.07 to get $100 pre-tax, and the tax portion is $7. The effective rate here is $7 ÷ $107 = 6.54% of the total, which is why reverse-calculated tax always looks slightly smaller than the headline rate applied to the pre-tax amount.

US Sales Tax Basics

The United States does not have a federal sales tax. Instead, sales tax is set by state and local governments, which means the rate you pay depends on where you make the purchase. Forty-five states and the District of Columbia levy a statewide sales tax, and many counties and cities add a local tax on top. As a result, the combined rate at checkout can be notably higher than the state's base rate. Five states — Alaska, Delaware, Montana, New Hampshire, and Oregon — do not levy a statewide sales tax, though Alaska allows local jurisdictions to impose their own.

Why Combined Rates Matter

When you look up a state's sales tax rate, you're usually seeing the state base rate. But many locations add 1% to 4% or more in local taxes, and some cities stack multiple local levies. Always use the combined rate for your specific location when calculating sales tax, otherwise you'll under-collect or under-estimate the tax. Online retailers are now generally required to collect sales tax based on the destination address, so the rate that applies to an online order is typically the combined rate where the item is shipped.

Tips for Working with Sales Tax

• Use the combined state + local rate, not just the state rate.
• Keep receipts — the total includes tax, and reverse mode helps you recover the pre-tax amount.
• Remember that some items (groceries, medicine, clothing in some states) are exempt or taxed at a lower rate.
• For business expense reports, reverse-calculate the tax from totals so your reimbursement matches pre-tax spend.
• When selling products, confirm whether shipping and handling are taxable in your jurisdiction.