How to use the sales tax calculator
Choose Add tax to a price when you know the sticker price and want the checkout total. Choose Remove tax from a total when you have a receipt or a tax-inclusive price and need the amount before tax — for an expense report, bookkeeping or checking an invoice. Enter the combined rate for the location where the sale takes place.
Sales tax formulas
Adding tax: tax = price × rate ÷ 100, and total = price × (1 + rate ÷ 100)
Removing tax: pre-tax price = total ÷ (1 + rate ÷ 100), and tax = total − pre-tax price
Worked examples
Adding: a $249.99 TV at a 7.5% rate. Tax = 249.99 × 0.075 = $18.75, so the total is $268.74.
Removing: a receipt shows $53.50 including 7% tax. Pre-tax price = 53.50 ÷ 1.07 = $50.00, so the tax was $3.50.
Don't back out tax by taking a percentage of the total
A tempting shortcut is to take 7% of the $53.50 total. That gives $3.75 — 25 cents too much — because it charges tax on the tax. The error grows with the amount: on a $10,700 tax-inclusive invoice the shortcut says $749 in tax when the true figure is $700. Always divide by (1 + rate) first.
Why your rate is probably not the state rate
In most states the rate at the register is a stack: a statewide rate plus county and city taxes, and sometimes special-district taxes that fund transit or other projects. Two stores a few miles apart can charge different rates, and one ZIP code can contain more than one tax jurisdiction. Alaska, Delaware, Montana, New Hampshire and Oregon have no statewide sales tax, although many Alaska communities levy a local one.
To find the rate that applies to you:
- Check a recent receipt from a store nearby. Divide the tax by the taxable subtotal and multiply by 100 to get the combined rate.
- Use your state department of revenue's lookup tool. Most states let you look up the rate for a specific street address.
- Recheck periodically if you run a business. Local rates can change during the year, so confirm against your state's official rate tables.
What gets taxed varies too
Each state decides which goods and services are taxable. Groceries, prescription drugs, clothing and services are treated very differently from one state to the next, and some items are taxed at a reduced rate. If you buy from an out-of-state seller that does not collect tax, your state may expect you to pay use tax at the same rate. For shopping math, pair this with the discount calculator.
Frequently asked questions
How do I calculate sales tax?
Multiply the price by the rate written as a decimal. At 6.5%, a $40 purchase carries 40 × 0.065 = $2.60 in tax, for a total of $42.60.
How do I find the price before tax from a total?
Divide the total by one plus the rate as a decimal. A $64.20 total at 7% was 64.20 ÷ 1.07 = $60.00 before tax.
Is sales tax charged before or after a discount?
Store discounts generally reduce the taxable price, so tax is figured on the discounted amount. Manufacturer coupons are treated differently in some states, where tax is charged on the price before the coupon.
Is shipping subject to sales tax?
It depends on the state. Some tax delivery charges, others exempt them when they are listed separately on the invoice. Your state revenue department publishes the rule.
Why is my receipt a cent different from the calculator?
Sellers round tax to the nearest cent, and some round each line item separately rather than the whole order. Small rounding differences of a cent or two are normal.
Last updated: October 8, 2026