Sales Tax Calculator

How to use this calculator#

1. 1
   Choose add or extract firstAdd mode takes a shelf price and tells you what the register will charge. Extract mode takes a receipt total and tells you how much of it was tax — the number you need for an expense claim or a VAT-style bookkeeping entry.
2. 2
   Enter the combined rate, not just the state rateUS sales tax stacks state, county, city and special district levies. Chicago reaches 10.25% against an Illinois state rate of 6.25%, so entering the state figure alone understates the bill by two thirds of the tax.
3. 3
   Use the delivery address for online ordersSince the 2018 Wayfair decision, remote sellers charge based on where the goods arrive, not where the seller sits. Look up the rate for the shipping ZIP code rather than your billing address.
4. 4
   Check whether the item is even taxableGroceries, prescription drugs and — in a handful of states — clothing are exempt or reduced. Applying the general rate to an exempt item produces a total that will never match the receipt.

The formula#

Adding tax versus extracting it#

Adding tax is easy: tax = price x rate / 100, so 80 at 8.25% adds 6.60 for a total of 86.60. Extracting is where people slip up, because you cannot simply take 8.25% of the gross. The correct step is net = gross / (1 + rate / 100), so 86.60 divided by 1.0825 returns exactly 80.00 with 6.60 of tax.

Taking 8.25% of 86.60 instead gives 7.14, overstating the tax by more than half a dollar on a single receipt. Across a month of expenses that error compounds into a real discrepancy, which is why every bookkeeping system divides rather than multiplies when working backwards from a tax-inclusive figure.

How US sales tax stacks up#

US sales tax is layered: a state rate plus county, city and sometimes special district rates on top. Chicago reaches 10.25% while Portland, Oregon charges nothing at all. Five states — Alaska, Delaware, Montana, New Hampshire and Oregon — levy no statewide sales tax, though individual Alaskan boroughs add local ones. For most online orders the rate follows the delivery address, not the seller.

Groceries, prescription drugs and clothing are exempt or reduced in many states, and several run annual back-to-school tax holidays. Unlike VAT, sales tax is charged only at the final retail sale and quoted separately from the shelf price, which is why the number on the tag is never the number on the receipt.

Worked examples#

Reference tables#

Common mistakes#

• Multiplying the gross by the rate to find the taxOn an $86.60 total at 8.25%, multiplying gives $7.14 when the real tax is $6.60. The overstatement grows with the rate and the amount, and it silently inflates every expense claim and input-tax entry it touches.
• Using the state rate instead of the combined rateIllinois charges 6.25% statewide; Chicago charges 10.25%. Quoting the state figure to a customer and then charging the combined one is a chargeback conversation, and quoting it in a budget understates your costs by a third.
• Charging tax on the pre-discount priceSales tax applies to the amount the customer actually pays. A 25% discount on a $200 jacket means tax on $150, not $200. The exception in several states is a manufacturer's coupon, where the retailer is reimbursed and tax is computed on the original price.
• Treating shipping and handling as automatically taxableRules diverge sharply: some states tax delivery whenever the goods are taxable, others exempt separately stated shipping, and a few tax handling but not freight. Getting this wrong on high-volume small orders is a common audit finding.

Frequently asked questions#

Key terms#

Combined rate

State plus county, city and special district rates — the number actually charged at the register, and the one to enter here.

Nexus

The connection that obliges a seller to collect tax in a state. Since South Dakota v. Wayfair (2018) it can be created by sales volume alone, with no physical presence.

Use tax

The mirror of sales tax, owed by the buyer when an out-of-state seller did not collect it. Widely owed, rarely paid, and routinely assessed on business audits.

Exemption certificate

A document letting a buyer purchase without tax — typically for resale, manufacturing inputs or a non-profit. The seller must hold a valid one or become liable for the tax.

Tax holiday

A short window when a state suspends sales tax on defined categories, usually school supplies, clothing or storm preparedness items.

Tax-inclusive vs tax-exclusive

US prices are quoted tax-exclusive, so the shelf price is not the checkout price. VAT and GST countries quote tax-inclusive prices to consumers by law.

Sources#