Sales Tax Calculator

Sales tax turns a shelf price into a different checkout price, and this calculator works the problem both directions: add a tax rate to a price to get the total, or start from a tax-inclusive total and back out the pre-tax price and the tax itself — the second job being the one receipts and bookkeeping actually demand.

What is sales tax?

Sales tax is a consumption tax collected by the seller at the point of sale and remitted to state and local governments. In the US there is no national sales tax and no single rate: states set a base rate (five states set it to zero), and counties and cities stack their own on top, so the combined rate at a given register ranges from 0% to over 10% depending on the exact address of the sale. The tax usually applies to goods, with services taxed in some states and categories like groceries and prescription medicine exempt or reduced in many.

The two calculations this page performs cover the practical cases. Forward — price times rate, added on — is the shopper's question: what will this actually cost? Backward — extracting the tax from an inclusive total — is the bookkeeper's and the traveler's question: a receipt shows $128.70 paid; how much was the item and how much was tax, for expense reports, reimbursements, business deductions, and pricing comparisons across jurisdictions. The backward direction is where people err, subtracting the rate from the total instead of dividing, and the How section explains why division is correct.

For online purchases, US rules after the South Dakota v. Wayfair decision let states require remote sellers to collect tax based on the delivery address once the seller passes an economic threshold in that state — which is why your cart's tax line is computed from your ZIP code, and why the same item can total differently shipped to different states. Enter the rate that applies where the purchase is delivered, which for most orders is the rate the checkout itself will show.

How sales tax is calculated

Adding tax is one multiplication and one addition: tax = price × rate, total = price + tax. Extracting tax from an inclusive total is the inverse operation — and the inverse of 'multiply by (1 + rate)' is 'divide by (1 + rate),' not 'subtract the rate.' If $128.70 includes 7.25% tax, the pre-tax price is $128.70 ÷ 1.0725 = $120.00, and the tax is the $8.70 remainder. Subtracting 7.25% of $128.70 ($9.33) would understate the price, because the percentage was originally applied to the smaller pre-tax base — the same base-asymmetry that governs percentage change.

Retailers compute tax per transaction with rounding to the cent, and a few jurisdictions use bracket schedules; your result may differ from a register by a cent on some amounts. Multi-item carts are usually taxed on the summed taxable subtotal, not item by item, which can shift a cent as well. For estimates, budgeting, and expense breakdowns, the calculator's figure is the correct one.

Keep the two rates in your life straight: the rate where you live applies to most in-store purchases there, but big-ticket items bought across a state line can trigger 'use tax' owed to your home state — the mirror-image obligation most states technically impose on residents for out-of-state purchases. The calculator does not track which jurisdiction's rate you owe; it applies whichever rate you enter to the amount you enter.

Businesses sit on both sides of this tax: they collect it on sales (a liability held in trust, never revenue) and they generally do not pay it on goods bought for resale or as manufacturing inputs, using exemption certificates instead. If your 'price' is a business purchase for resale, the correct tax may be zero — a question for your state's rules, not for arithmetic.

Sales-tax holidays deserve a footnote in the same spirit: several states suspend the tax on defined categories for a few days a year. The correct calculation during a holiday is simply a rate of zero on the exempt items and the normal rate on everything else in the same basket — run the taxable and exempt subtotals separately through this calculator rather than inventing a blended average rate, which would misstate both halves.

Worked example

A $120 item in a jurisdiction with a 7.25% combined rate. The calculator is pre-loaded in 'add tax' mode with these numbers; switch it to extract mode with $128.70 to run the example backwards.

The tax on $120 at 7.25% is exactly $8.70, for a checkout total of $128.70. The extract row proves the round trip: dividing the inclusive total by 1.0725 returns the $120.00 base and the same $8.70 tax. Had you (incorrectly) subtracted 7.25% from $128.70, you would have booked the price as $119.37 — a small error per receipt that scales into real money across a year of expense reports.

Finding your combined rate

The rate to enter is the combined state, county, city, and any special-district rate at the place of sale (or delivery, for shipped goods). State revenue departments publish rate lookup tools by address, and the rate printed on any recent local receipt is the fastest source: divide the tax line by the taxable subtotal and you have your combined rate to two decimals. Rates change as local levies are enacted or expire, so a rate memorized years ago may be stale by a fraction of a point.

Note the common exemptions when estimating a real purchase: many states exempt groceries and prescription drugs entirely or tax them at a reduced rate, while taxing restaurant meals and prepared food at the full rate (sometimes plus a meals surcharge). Clothing is exempt in a few states, famously Pennsylvania and Minnesota, and several states run tax-free weekends on categories like school supplies — the arithmetic stays the same, only the rate or the taxable base changes.

Sales tax for sellers and expense reports

If you sell, the tax you collect is not income: it is the state's money passing through your register, and it must be separated in your books from revenue — exactly the extraction calculation, run on every tax-inclusive deposit. Marketplaces now collect and remit on behalf of sellers in most states, but direct sales usually remain the seller's obligation, with filing frequencies set by volume.

For expense reports, extract mode answers the recurring question of how much of a receipt total was deductible goods versus nondeductible or separately-reported tax. Run each receipt's total through the calculator at the local rate, and the split is consistent, auditable, and arithmetically correct — unlike the subtract-the-rate shortcut, which misstates every single entry in the same direction.

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