🧾 Sales Tax Calculator: Add or Reverse VAT, GST and Tax

What is the Sales Tax Calculator?

Sales tax is a percentage that a government adds to the price of goods and services at the point of sale. In the United States it is called sales tax and is normally added at the register on top of the listed price, so a $100 item at an 8.25% rate costs $108.25 at checkout. In most of Europe, the United Kingdom, Canada, Australia, and many other countries the equivalent is called VAT (value added tax) or GST (goods and services tax), and the rate is usually already included in the shelf price you see. This calculator handles all of them because they are all flat percentage rates: you simply supply the rate that applies to your purchase or sale.

Adding tax is straightforward: multiply the net amount by the rate and divide by 100 to get the tax, then add it to the net amount to get the total. A $100 sale at 8.25% gives $8.25 of tax and a $108.25 total. The harder direction, and the one people get wrong most often, is working backwards from a tax-inclusive price to find the original amount. You cannot just subtract the rate, because the rate was applied to the smaller net figure, not the larger total. The correct reverse formula is net = total / (1 + rate / 100). For a $108 total at an 8% inclusive rate, net = 108 / 1.08 = $100.00, so the tax portion is $8.00. This reverse calculation is exactly what you need when you have a gross receipt and have to report the net sale and the tax separately, which is common for bookkeeping, VAT returns, and expense claims.

In the United States there is no single national sales tax rate. The rate you actually pay is a combination of a state rate plus county, city, and special district rates, so two addresses a few miles apart can have different totals. Five states levy no statewide sales tax at all: Alaska, Delaware, Montana, New Hampshire, and Oregon. Alaska is a special case because, while it has no state rate, many localities add their own, so a purchase there may still be taxed. At the other end, combined state and local rates can exceed 10% in states such as Louisiana, Tennessee, Arkansas, and Washington. Because rates change and vary by exact location, always confirm the current combined rate for the specific address before relying on a calculation.

What gets taxed also varies. Most states tax tangible goods but exempt or reduce the rate on certain essentials. Groceries, prescription drugs, and in some states clothing are commonly exempt or taxed at a lower rate, while prepared restaurant food, electronics, and most general merchandise are fully taxable. Services were historically untaxed in many states but are increasingly being brought into the tax base. If you are a seller, this distinction matters because charging tax on an exempt item, or failing to charge it on a taxable one, can create compliance problems later.

For online and out-of-state sales, the rate often depends on sourcing rules and nexus. Most states are destination-based, meaning the rate is set by the buyer's shipping address rather than the seller's location, while a handful are origin-based and use the seller's location for in-state sales. A business only has to collect tax in states where it has nexus, which is a physical or economic presence such as a warehouse, employees, or sales above a state threshold. This calculator does not look up rates or nexus for you, but once you know the correct combined rate, it gives you the exact tax and total in one step.

Sales tax can also matter at tax-filing time. If you itemize deductions on Schedule A of a US federal return, you may deduct either your state and local income taxes or your state and local general sales taxes, but not both. The sales tax option is often the better choice for residents of no-income-tax states or anyone who made large taxable purchases during the year. You can total your actual receipts or use the IRS optional sales tax tables, which estimate a deduction from your income, family size, and state. Use this calculator to verify the tax on individual large purchases such as a vehicle or appliance that you add on top of the table amount.

When to use it

• Adding US sales tax to a price so you know the real checkout total before you buy.
• Extracting the VAT or GST from a tax-inclusive receipt for bookkeeping or a tax return.
• Quoting a customer a net price plus tax, or working out the net from a gross invoice total.
• Comparing how different state or country tax rates change the final price of the same item.
• Checking the tax on a large purchase such as a car or appliance for a sales tax deduction.
• Splitting a gross receipt into net sale and tax for VAT, GST, or sales tax filing.

How to use the Sales Tax Calculator

1. Choose "Add tax" to put tax on top of a net price, or "Extract tax" to pull tax out of a tax-inclusive total.
2. Enter the amount: the net price in Add mode, or the tax-inclusive total in Extract mode.
3. Type the tax rate as a percentage, or tap one of the quick-rate buttons.
4. For a US purchase, use the combined state plus local rate for the exact address, not just the state base rate.
5. Read off the net amount, the tax amount, and the total with tax.

Formula & method

Worked examples

Common tax rates by region (illustrative, confirm current local rates)

US states with no statewide sales tax

Add tax vs extract tax at a 10% rate

Common mistakes to avoid

• Subtracting the rate to remove tax. To take 20% VAT off a £120 total, people subtract 20% (£24) and get £96, which is wrong. The tax was applied to the smaller net amount, so you must divide by 1.20, giving £100 net and £20 tax.
• Mixing up the net price and the tax-inclusive total. In Add mode the amount you type is the price before tax. In Extract mode it is the price that already includes tax. Entering the wrong one gives a tax figure that is off in either direction.
• Assuming the listed price already includes tax. In the US, sales tax is usually added at the register, so the shelf price is the net amount. In most VAT and GST countries the price already includes tax. Know which applies before you calculate.
• Using only the state base rate for a US purchase. The rate you actually pay is the state rate plus county, city, and district rates combined. Using just the state base rate understates the tax, since combined rates can run several points higher.
• Taxing the price before applying a discount. Sales tax is normally charged on the amount actually paid, so apply coupons and discounts first, then add tax to the reduced price rather than the original sticker price.
• Using a stale or wrong local rate. Combined US sales tax varies by state, county, and city, and VAT or GST rates change over time. Always confirm the current rate for the exact location rather than reusing an old figure.

Glossary

Sales tax

A percentage tax added to the price of goods and services, typically added at checkout in the United States.

VAT

Value added tax, a consumption tax used across the UK, EU, and many other countries, usually included in the displayed price.

GST

Goods and services tax, a broad consumption tax used in countries such as Australia, Canada, and India.

Net amount

The price before any tax is added. Tax is calculated as a percentage of this figure.

Gross amount

The tax-inclusive total: the net amount plus the tax on it.

Combined rate

The total US sales tax rate at an address, made up of the state rate plus any county, city, and special district rates.

Nexus

A physical or economic connection to a state that requires a seller to collect that state's sales tax.

Sales tax deduction

An itemized federal deduction for state and local sales taxes paid, claimed on Schedule A instead of state income tax.

Frequently asked questions