Sales Tax Calculator

Background.

A $100 pair of headphones in a New York City electronics shop rings up at $108.88. A £100 price on a shelf in London is what you hand over, because VAT is already inside it. The two receipts use the same arithmetic run in opposite directions, and both directions are here: add tax to a pre-tax price, or extract it from a total that already includes it.

In the United States the price on the tag is almost always before tax. Forty-five states and the District of Columbia levy a statewide sales tax, and most of them let counties, cities and special districts stack their own percentages on top, so the rate depends on exactly where the sale takes place. New York City's 8.875% is a typical stack: 4% for the state, 4.5% for the city and 0.375% for the Metropolitan Commuter Transportation District. Only Alaska, Delaware, Montana, New Hampshire and Oregon have no statewide sales tax, and Alaska still lets its towns and boroughs charge one.

Across the UK, the European Union, Australia and much of the rest of the world, the equivalent tax is a value added tax or a goods and services tax, and prices shown to shoppers include it. There the everyday problem runs backwards: you hold a total and need to split it into the net price and the tax, for an expense claim, a set of books or a VAT return.

Running it backwards is where people go wrong. The tax on a $100 item at 8.875% is $8.88, but 8.875% of the $108.88 total is $9.66, because the percentage has been applied to the wrong base. To take tax out of a total you divide by one plus the rate; you do not multiply by the rate.

The rate you enter is one combined percentage. Which goods are taxable, which local districts apply and whether delivery counts are matters of state or national law, and you need to settle them before the arithmetic means anything.

What is sales tax calculator?

A sales tax is a tax on the retail sale of goods and, in some places, services, collected by the seller from the buyer at the moment of sale and paid over to the government on a periodic return. The buyer bears the cost; the seller acts as collector. American sales tax is tax-exclusive, so the tax is added on top of the marked price. A value added tax reaches the same final shopper by a different route: every business in the supply chain charges VAT on its sales and reclaims the VAT it paid on its own purchases, so only the value it added is taxed at each step. At the same rate, a single-stage retail sales tax and a VAT leave the final consumer paying the same amount; the difference lies in who collects it and when.

Two other taxes can sit on the same bill without being sales tax. Excise taxes fall on particular goods, such as motor fuel, alcohol and tobacco, often as a fixed amount per gallon or per pack, and are charged in addition to, or sometimes instead of, the general rate. Gross receipts taxes, such as Washington's business and occupation tax or Ohio's commercial activity tax, are charged to the seller on its revenue with no exemption for sales to other businesses, and usually do not appear as a separate line on your receipt.

How to use this calculator.

1. 01Choose the mode. Pick Add when you know the sticker price and want the amount due at the register; pick Extract when you hold a total that already includes tax, such as a European receipt, the gross figure on a VAT invoice or an all-in quote.
2. 02Enter the price: the pre-tax amount in Add mode, the tax-inclusive total in Extract mode. The dollar sign is only a label; pounds, euros, Canadian dollars or shillings work identically.
3. 03Enter the combined rate at the place of sale, meaning state plus county plus city plus any special district. Your state revenue department's address lookup gives it exactly; failing that, divide the tax on a recent receipt from the same shop by its taxable subtotal. For VAT, use the rate for that kind of goods, not always the standard one.
4. 04Read the pre-tax price, the tax and the total. In Extract mode the pre-tax figure is the net amount for your books and the tax line is what goes to the tax account or the VAT reclaim.
5. 05Glance at the effective rate. It reads back the rate you entered, confirming which percentage was applied before you copy the figures anywhere.

The formula.

Add mode treats the price P as pre-tax. Tax = P × r ÷ 100, and Total = P + Tax, which is the same as P × (1 + r/100). At 8.875% the multiplier is 1.08875.

Extract mode treats the price as a total T that already contains the tax. Since T = Pre × (1 + r/100), the pre-tax price is Pre = T ÷ (1 + r/100), and the tax is whatever is left: Tax = T − Pre. Written another way, the tax is T × r ÷ (100 + r), which shows why the share of a total that is tax is always smaller than the rate. At 8.875%, tax is 8.15% of the total. At the UK's 20% standard rate the share is exactly one sixth, which HMRC calls the VAT fraction; at Australia's 10% GST it is one eleventh.

Each money figure is rounded to the nearest cent, with an exact half cent going up, so the $8.875 of tax on a $100 price is shown as $8.88. The effective rate is worked out from the unrounded tax and pre-tax amounts, so it always matches the rate you typed.

The rate box accepts anything from 0% to 50%, and the price must be above zero. Two taxes charged on the same pre-tax base can simply be added into one rate: Quebec's 5% GST and 9.975% QST, both levied on the price before either tax, make 14.975%. A tax charged on top of another tax would need two separate runs, the second starting from the first total.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Tax Foundation — 2025 State and Local Sales Tax Rates (annual rankings of combined state plus local rates)
2. [2]South Dakota v. Wayfair, Inc., 138 S. Ct. 2080 (2018) — Supreme Court decision establishing economic nexus for state sales tax collection on remote sellers
3. [3]IRS Schedule A Instructions (2025) — State and Local General Sales Tax deduction guidance, including the optional sales tax tables that replaced Publication 600
4. [4]OECD Consumption Tax Trends 2024 — Comparative analysis of VAT and retail sales tax systems across OECD member countries
5. [5]HMRC VAT Notice 700 — The VAT Guide (UK operational reference for tax-inclusive pricing and VAT arithmetic)
6. [6]Council Directive 2006/112/EC — EU common system of value added tax (legal basis for EU VAT rates and tax-inclusive retail pricing)
7. [7]New York State Department of Taxation and Finance — Sales and Use Tax Rates by Locality (Publication 718)
8. [8]California Department of Tax and Fee Administration — Sales and Use Tax Rates by City and County