How This Calculator Works
Choose which value you want to solve for — the total price with tax added, the pre-tax price with tax removed, or the tax rate itself — then enter the other two values. The field you're solving for is highlighted and fills in automatically as you type, so there's never a button to hunt for or a wrong-direction subtraction to worry about.
If you are setting a price rather than checking one, it is worth knowing the volume that price has to reach. Our break-even calculator turns a price and a cost base into the units you need to sell.
The Sales Tax Formula (Forward and Reverse)
Adding tax to a price is straightforward: tax amount = price before tax × (rate ÷ 100), and total price = price before tax + tax amount. At a $100 price and an 8% rate, that's $100 × 0.08 = $8.00 in tax, for a $108.00 total.
Going the other direction is where people most often make a mistake. Given a $108 total, it's tempting to just subtract 8% of $108 (which would be $8.64), but that's wrong — the 8% rate was applied to the original $100, not to the $108 total. The correct reverse formula is price before tax = total ÷ (1 + rate ÷ 100): $108 ÷ 1.08 = $100.00 exactly, with the $8.00 tax amount following from there.
Sales Tax vs. VAT and GST
Sales tax, used across the United States, is collected once — at the final sale to the end consumer — with the retailer passing the full amount to the state or local government. Most of the rest of the world instead uses a value-added tax (VAT) or goods and services tax (GST), which is collected in smaller pieces at every stage of production and distribution, with each business reclaiming the tax it paid to its own suppliers. The end consumer's out-of-pocket cost often ends up similar either way, but the collection mechanism — and who has to track and remit what — is quite different. If you need VAT-specific math (since VAT is more commonly quoted as already included in a displayed price), our VAT calculator handles that directly.
Which States Have No Sales Tax?
Five US states charge no statewide sales tax at all: Alaska, Delaware, Montana, New Hampshire, and Oregon — sometimes remembered by the acronym NOMAD. Delaware, Montana, New Hampshire, and Oregon also don't allow local sales taxes, so a purchase in those four states genuinely carries no sales tax anywhere. Alaska is the exception on the list — while there's no state-level sales tax, Alaska does let individual boroughs and municipalities levy their own local sales tax, so some purchases there can still carry a small combined rate depending on exactly where you are.
How Combined Sales Tax Rates Work
In the 45 states (plus DC) that do charge sales tax, what you actually pay at checkout is typically a combined rate stacking several layers: a state rate set by the state government, plus in most places an additional county rate, and often a city or special-district rate on top of that. Two stores a few miles apart, in different counties or just across a city line, can charge noticeably different combined rates on an identical item. This is exactly why this calculator asks for your own combined rate rather than guessing from a state name — a single "state rate" would be wrong for the large majority of actual purchases within that state.
Frequently Asked Questions
What's the formula for calculating sales tax?
Sales tax amount = price before tax × (tax rate ÷ 100). The total price is simply the price before tax plus that tax amount, or equivalently price before tax × (1 + tax rate ÷ 100). For example, a $100 item at an 8% rate adds $8.00 in tax for a $108.00 total.
How do I find the pre-tax price from a total?
Divide the total by (1 + tax rate ÷ 100) — do not simply subtract the tax percentage from the total, since the rate applies to the pre-tax price, not the total, and subtracting it directly overstates the tax removed. For a $108 total at 8%, dividing by 1.08 correctly gives a $100 pre-tax price, not $99.36.
Which US states have no sales tax?
Five states have no statewide sales tax: Alaska, Delaware, Montana, New Hampshire, and Oregon (sometimes remembered by the acronym NOMAD). Alaska does allow local municipalities to charge their own sales tax, so a purchase there can still carry tax depending on the city or borough.
Why do I have to enter my own tax rate instead of picking my state?
Combined sales tax rates in the US are set across more than 11,000 local jurisdictions, since state, county, and city rates stack differently almost everywhere — two addresses a few miles apart can have different combined rates. Rather than risk showing a stale or wrong number, this calculator asks for the combined rate you already know applies, and does the math instantly.
What's the difference between sales tax and VAT or GST?
Sales tax is charged once, at the final sale to the end consumer. VAT (value-added tax) and GST (goods and services tax), used across most of the world outside the US, are instead collected incrementally at every stage of production and distribution, with businesses reclaiming what they paid at earlier stages. The end consumer's total cost often works out similarly, but the collection mechanism is quite different.
Can I use this to calculate a discount or tip instead?
This calculator is built specifically for tax math (adding or removing a percentage that applies on top of a price). For a discount taken off a price, or for calculating a tip, use a dedicated discount calculator or tip calculator instead, since the direction of the percentage and typical rounding conventions differ.
This calculator provides general estimates only. Confirm your jurisdiction's exact combined sales tax rate with a local source before relying on this for accounting, pricing, or filing purposes.