Stepwise.

Sales Tax Calculator

Add sales tax, VAT or GST to a price, or strip it back out of a tax-inclusive total to find the net amount.

How to use this calculator

  1. 1Choose whether you are adding tax to a net price or extracting it from a total.
  2. 2Enter the amount and the combined tax rate that applies.
  3. 3Use quantity to scale an invoice line to its total.

How the calculation works

Adding: Gross = Net × (1 + r) Removing: Net = Gross / (1 + r)
Net
Price before tax
Gross
Price including tax
r
Tax rate as a decimal (8.25% = 0.0825)

The reverse calculation divides rather than subtracts. On a $108.25 gross at 8.25%, the tax is $8.25 — but 8.25% of $108.25 is $8.93, which is why subtraction gives the wrong net price.

The tax always represents a smaller share of the gross than the nominal rate, because the rate is applied to the smaller net figure.

Worked example

Removing 8.25% tax from a $108.25 receipt total

  1. 1.Net = 108.25 ÷ 1.0825 = $100.00.
  2. 2.Tax = 108.25 − 100.00 = $8.25.
  3. 3.Note that 8.25% of $108.25 would be $8.93 — subtracting the rate from the gross would have given a net of $99.32, which is wrong.

Result: $100.00 net, $8.25 tax

What sales tax actually is

Sales tax is a consumption tax — charged on the sale of goods and services rather than on income or profit — collected by the seller at the point of sale and passed on to the government. Economically, the customer bears the cost, but the legal obligation to collect and remit it usually sits with the business making the sale, which is why a mistake in sales tax handling is a compliance problem for the seller even though the seller never gets to keep the money.

Sales tax, VAT and GST — different systems, similar goal

Most of the world raises consumption tax through one of a few structurally different systems, even though the effect on the final price often looks similar.

  • US-style sales tax — charged once, at the final retail sale to the end consumer, and generally not applied to business-to-business transactions further up the supply chain.
  • Value-added tax (VAT) — used across the European Union, the UK and much of the world, charged at every stage of production, with businesses able to reclaim the VAT they paid on their own purchases — so only the final consumer ends up bearing the full cost.
  • Goods and services tax (GST) — functionally very similar to VAT, and the term used in countries including Canada, Australia and India, sometimes layered alongside separate regional taxes.

Why rates vary so much, even within one country

In the United States there is no federal sales tax at all — every rate is set at the state level or below, and most states allow counties, cities and special districts to add their own additional rate on top. Two addresses a few streets apart can carry meaningfully different combined rates, which is why looking up the exact rate for a specific address is more reliable than assuming a state’s headline figure applies everywhere within it. VAT and GST systems tend to be more uniform nationally, but often carry reduced or zero rates for categories like groceries, books or children’s clothing.

Who actually collects and remits it

A business selling taxable goods or services generally has to register with the relevant tax authority, charge the correct rate at checkout, and periodically file a return remitting what it collected. Online and remote sellers were largely exempt from this in the US for decades unless they had a physical presence — a store, warehouse or employee — in the buyer’s state. That changed with a 2018 US Supreme Court decision, South Dakota v. Wayfair, which allowed states to require out-of-state sellers to collect tax once their sales into that state cross a set threshold, even with no physical presence at all. Most states with a sales tax adopted a version of this "economic nexus" rule within a few years of the ruling.

How the system has evolved

Consumption taxes are much older than income tax in most countries, but the VAT model itself is comparatively recent — France introduced an early modern version in the 1950s, and it spread across Europe and much of the world over the following decades, in part because it is harder to evade than a single-stage sales tax collected only at the final sale. The US never adopted VAT nationally and instead kept its patchwork of state and local sales taxes, a structural difference that still shapes how the two systems are administered today.

What this assumes, and where it stops

Assumptions

  • A single combined tax rate applies to the whole amount.
  • The item is taxable at the standard rate for your jurisdiction.

Limitations

  • US sales tax rates combine state, county, city and district levies and vary by exact address. Look up your rate rather than assuming the state rate.
  • Reduced and zero rates for food, books, children’s clothing and similar categories are common in VAT systems and are not applied automatically.
  • Does not handle compound taxes where one tax is charged on top of another, as in some Canadian provinces historically.

Common questions

How do I work out the tax from a total that already includes it?

Divide the total by (1 + rate). At 20% VAT, divide by 1.2 to get the net, then subtract to get the tax. A common shortcut for 20% VAT is to divide the gross by 6 — that gives the VAT directly.

Is sales tax calculated before or after a discount?

Almost always after. The tax applies to the amount the customer actually pays, so a discount reduces the taxable base. Manufacturer rebates are sometimes treated differently from retailer discounts.

Sources

Formula and content last reviewed on .

Results are estimates for information only, not professional advice.

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