US sales tax formula and examples
Enter the pretax price and a verified combined tax percentage. Tax = pretax price × rate ÷ 100; total = pretax price + tax. A $100 purchase at an illustrative 8.25% produces $8.25 tax and $108.25 total. At 7.5%, a $80 purchase produces $6.00 tax and a $86.00 total.
Where to find an applicable tax rate
There is no single nationwide US sales tax rate. Taxable products, exemptions, state, county and city rules differ; consult official revenue agencies before entering a percentage. USAGov lists ways to find state and local tax agencies. Do not add a state rate to an already combined state-and-local rate.
What this calculator cannot determine
It cannot look up jurisdictions or establish taxability, shipping rules, seller obligations, exemptions or special tax rounding. It only performs arithmetic on your inputs. For a discounted pretax price use the discount calculator; for other percentage questions use the percentage calculator.
Additional example and FAQs
Sales tax in the United States is not a single nationwide rate. State, county, city, district, product category, exemptions and remote-seller rules can matter. Formula: sales tax = pretax amount × entered rate / 100; total = pretax amount + sales tax.
Example: a $100 purchase at an illustrative 8.25% combined rate generates $8.25 in tax and a $108.25 total. The rate is an example, not a suggested rate for any jurisdiction. Confirm the actual rate and taxable basis with authoritative local guidance.
Frequently asked questions
Does this determine the correct state and local tax rate?
No. You must find and enter the correct combined rate from an official source.
Is 8.25% the standard US rate?
No. It is only a worked example, not a nationwide rate.
Reverse sales tax: remove tax from a total
Switch the calculator to Remove sales tax from total when you know the tax-inclusive amount and the tax rate. The formula is pretax amount = total ÷ (1 + rate ÷ 100); the tax amount is the difference between total and pretax amount. At 8.25%, a total of $108.25 contains $100.00 pretax and $8.25 sales tax, before considering jurisdiction-specific rounding or product exemptions.
Use only a rate you have verified for the applicable location, sale and product. This calculation does not determine whether a purchase is taxable, perform a ZIP-code lookup or handle fees that are not part of the sales-tax percentage.
Reverse sales tax versus a percentage discount
Removing 8.25% sales tax from a $108.25 total is not the same as applying an 8.25% discount. The correct pretax calculation divides $108.25 by 1.0825 to get $100.00; taking an 8.25% discount would produce a different answer. Choose Remove sales tax from total for the reverse calculation and use the discount calculator for promotions or markdowns.
Price calculations beyond sales tax
To compare two product sizes fairly, use the unit price comparison tool; it focuses on quantity rather than tax liability. If your task is a promotional price reduction, use the discount calculator, not the reverse-tax formula.
Reverse sales tax calculator: price before tax
To reverse sales tax when the listed total already includes the tax, choose Remove sales tax from total and enter a verified combined rate. A $108.25 tax-inclusive total at 8.25% gives a pretax price of $100.00 and a tax component of $8.25. Use the reverse example button to load this scenario. The formula is before-tax price = total ÷ (1 + rate ÷ 100).
Reverse sales tax in a spreadsheet
For a tax-inclusive price in cell A2 and a percentage-formatted combined rate in B2, use =A2/(1+B2). If B2 contains the number 8.25 instead of 8.25%, use =A2/(1+B2/100). Do not simply subtract 8.25% from the tax-inclusive price: that calculates a discount, not a tax reversal.
Does this work for a particular US state?
The arithmetic works with any valid rate you enter, but it does not find the applicable state, county, city or special-district rate. Tax bases, exemptions and rounding may vary. Do not apply a combined rate to an item that has different taxability.