Free calculator · United States
Sales tax calculator: add or remove sales tax
Enter your state and local rates added together.
Type a price to see the tax.
You will get the price before tax, the tax itself and the total.
How US sales tax works (the short, honest version)
If you are used to VAT or GST, US sales tax can feel strange, because there is no federal sales tax at all. It is a patchwork: states charge it, and counties, cities and special districts often add their own on top. The same item can carry different tax in two neighbouring towns. A few things follow from that.
- You use one combined rate. Add the state, county, city and any district rates together, and enter the total in the rate box.
- The tax is on the sale, not on each stage. Businesses buying to resell generally do not pay it (that is what a resale certificate is for), and the end customer does.
- Where the rate comes from can differ. Some states tax at the seller’s location (origin), others at where the buyer is (destination). For online sales, destination is increasingly the rule.
- Not everything is taxed. Groceries, clothing, medicine and services are exempt in some states and taxed in others.
The maths
Adding sales tax
Tax = price × rate ÷ 100
Total = price + tax
$100 at 8.875%: tax = $8.875, rounded to $8.88. Total $108.88.
Finding the price before tax
Price = total × 100 ÷ (100 + rate)
Tax = total − price
$54.00 with 8% inside: 54 × 100 ÷ 108 = $50.00. Tax is $4.00.
Amounts are rounded to the nearest cent, half up. Some states ask for rounding on the whole invoice rather than on each line, so a long invoice can differ by a cent from adding up line-by-line figures. Your state’s revenue department says which it expects.
Why we do not look up your rate
Many sites offer a drop-down of states with a rate next to each. We chose not to. Those figures are only the state part, and the real rate for your customer is often higher once local taxes are added. A confident-looking wrong number is the kind of mistake that surfaces in an audit. So the box is yours to fill, from your state’s own published rate.
Putting it on an invoice
Our free invoice maker has a United States mode: you type your tax rate per item (set it to 0 for a customer who is exempt, for example with a resale certificate), and download a clean PDF with the sales tax shown on its own line. Inside a free account there is a proper tax-exempt switch on each customer.
Questions people ask
How do I calculate sales tax?
Multiply the price by your combined sales tax rate (as a percentage) and divide by 100, then add it to the price. At 8.875%, a $100 item has $8.88 of tax (8.875 rounds up to the next cent) and costs $108.88. The calculator above does it as you type.
What is my sales tax rate?
It is usually your state rate plus any county, city and special-district rates added together, and it can change from one street to the next. Your state's revenue department publishes the rates, and many have a lookup by address. We do not guess a rate for you, because a wrong guess is worse than an empty box.
How do I find the price before sales tax?
Choose 'Remove sales tax' and enter the total. The calculator divides by 1 plus the rate, so $108.88 at 8.875% comes back to $100.00 before tax. Subtracting a percentage of the total instead gives the wrong answer.
Which states have no sales tax?
Five states have no statewide sales tax: Alaska, Delaware, Montana, New Hampshire and Oregon. Alaska is the catch: many of its cities and boroughs charge local sales tax. Check before you assume.
Do I charge sales tax on shipping, or on services?
It depends on the state. Some tax shipping when the goods are taxable, others only when it is billed as part of the sale, and many do not tax shipping at all. Services are taxed in some states and not others. Look at your state's rules for the specific thing you sell.
When must an online seller collect sales tax in another state?
Since the Supreme Court's decision in South Dakota v. Wayfair (2018), a state can require out-of-state sellers to collect its tax once they pass a sales or transaction threshold there. Many states use $100,000 in sales or 200 transactions, but thresholds differ and change. Check each state where you sell a lot.
What is a resale certificate?
A form a business gives you to show it is buying goods to sell on, so it does not pay sales tax on that purchase. The final customer pays the tax. Keep a copy of every certificate: without one, you may owe the tax yourself if you are audited.
Checked against the official sources
Last reviewed on 11 October 2026. Tax rules and limits change, and we cannot see your whole situation, so treat this page as a guide, not advice. If something here looks out of date, the official pages below are the ones to trust, and we would be grateful if you told us.
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