Sales Tax Calculator

Add sales tax to a pre-tax amount or remove tax from a tax-inclusive total using any rate.

How is sales tax calculator worked out?

To add sales tax, multiply the pre-tax amount by the rate and add it. To find the tax inside a tax-inclusive total, divide the total by one plus the rate to get the net amount, then subtract that from the total.

Sales Tax Calculator

What do you want to do?Amount

The pre-sales tax amount when adding, or the sales tax-inclusive total when extracting.Sales tax rate

Use the rate that applies to what you are selling, where you are selling it.

Total with tax

$1,000.00

Sales tax at 0%: $0.00
Pre-tax amount: $1,000.00

Show the working

Pre-tax amount	$1,000.00
Sales tax at 0%	$0.00
Total with tax	$1,000.00

US sales tax is unusual among consumption taxes in being quoted separately from the shelf price and set locally: a state rate, often plus county and city rates, applied according to where the goods are delivered rather than where you are. That makes the arithmetic simple and the rate selection the hard part.

The formula

Adding tax:
Tax = pre-tax amount × rate ÷ 100
Total = pre-tax amount + tax

Extracting tax from an inclusive total:
Net = total ÷ (1 + rate ÷ 100)
Tax = total − net

The extraction formula is the one that catches people. Taking the rate off the inclusive total gives the wrong answer, because the percentage was applied to the smaller net figure in the first place.

Which rate applies to a sale

In most US states, sales tax is destination-based: the rate is the one in force where the customer takes delivery, combining state, county, city and sometimes special district rates. A handful of states use origin sourcing for in-state sales, several tax services differently from goods, and a few levy no state sales tax at all. Because the combined rate can differ between two addresses a few miles apart, the rate is worth looking up per transaction rather than remembering.

When you have to collect at all

Collecting sales tax depends on having nexus in the state — a connection created by physical presence or, since economic nexus rules became widespread, by exceeding a threshold of sales or transactions there. Thresholds and rules differ by state and change. Charging tax you are not registered to collect creates a liability you then have to remit; failing to charge it where you should leaves you owing money you never collected. Confirm your registration position with a tax professional rather than inferring it.

Frequently asked questions

How do you calculate sales tax?

Multiply the pre-tax amount by the tax rate expressed as a decimal. At a combined rate of 8.25%, a pre-tax amount of 200 attracts 16.50 of sales tax, for a total of 216.50.

How do I work out the sales tax in a sales tax-inclusive price?

Divide the inclusive total by one plus the rate as a decimal to get the net amount, then subtract that from the total. At a 20% rate, an inclusive total of 120 divides by 1.20 to give a net of 100 and sales tax of 20. Subtracting 20% from 120 gives 96, which is wrong — the percentage was calculated on the smaller net figure, not on the total.

What sales tax rate should I charge?

Generally the combined state and local rate for the address where the customer takes delivery, though sourcing rules and product taxability vary by state. Rates change and differ between neighbouring jurisdictions, so look up the current rate for the specific delivery address rather than applying a remembered figure.

Should sales tax be shown separately on an invoice?

Yes. Showing the tax as its own amount rather than folding it into the totals lets business customers account for it and keeps your own filing reconcilable against your invoices.

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