Sales Tax Calculator

Every sales tax sum starts from one known figure. The rate is written as a percentage, so a rate of r% is r in the formulas below.

Add sales tax to a price

Tax = price × rate ÷ 100, and total = price + tax. In one step, total = price × (1 + rate ÷ 100).

Reverse sales tax from a total

Tax = total × rate ÷ (100 + rate), and price = total − tax. In one step, price = total ÷ (1 + rate ÷ 100).

Find the price from the tax

Price = tax × 100 ÷ rate, and total = price + tax.

Find the rate from a receipt

Rate = (total − price) ÷ taxable part × 100, where the taxable part is the price before tax less any items on the receipt that were not taxed. The tax on the receipt was rounded to the cent, so the calculator also shows the band of rates that give the same tax.

The common mistake is taking the rate off a tax-inclusive total as though it were the price. The rate applies to the price before tax, so removing it means dividing the total by one plus the rate, not subtracting a percentage of the total.

In the United States sales tax is set by each state, and counties, cities and special districts can add their own rate on top, so the rate for a sale depends on where it takes place. This calculator does not look rates up by state, ZIP code or address and has none built in: type the combined rate that applies to you, as your state tax agency publishes it. Rates with three or four decimals are kept exactly, a comma or a point can be used as the decimal separator, and the rate in use is shown under the box so a mistyped one cannot quietly change every figure.

A ZIP code can straddle more than one tax area, so look the rate up by full address where your state offers it. Some state tax agencies' own lookups:

• California (CDTFA)
• Texas (Comptroller)
• New York (Department of Taxation and Finance)
• Washington (Department of Revenue)
• Ohio (The Finder)
• Minnesota (Department of Revenue)

For other states, use the lookup or rate list on your state's department of revenue website. These are other sites: we do not check their results and are not responsible for them.

A basket or an invoice often mixes items that are taxed with items that are not. In the list, untick Taxable on an exempt line: it counts toward the total and the exempt sales figure but carries no tax. Unit prices can be entered before tax, as on a quote, or including tax, as on a shelf price or a receipt, and the quantity can be a fraction.

Taxable sales and exempt sales are both reported before tax, so the two add up to the subtotal even when the unit prices were typed with the tax already in them. The Excel download reports them the same way.

Tax can be rounded to the cent on each line and added up, or worked once on the taxable total. On a long list the two can be a cent or two apart. The calculator works both, shows the difference under the list, and lets you choose which one the totals use, so an invoice agrees with itself whichever method you follow.

The Excel download keeps the rate, the tax-inclusive switch and the rounding method as cells at the top. Each line’s amount and tax, both rounding methods and the difference between them are live formulas, so changing a rate or ticking an item exempt recalculates the sheet.

This calculates sales tax on the figures and the rate you give it. It does not decide which rate applies, whether an item is exempt, whether you must collect tax in a state, or how a return is filed, and it is not tax advice.