Sales Tax Calculator
Both directions of the checkout math: add sales tax to a price at any combined rate, or start from a receipt total and extract the pre-tax price and the tax you actually paid.
Sales tax
Example: $49.99 at 8.25% → $4.12 tax, $54.11 total.
Forward and backward
Forward is familiar: $49.99 at a combined 8.25% rate adds $4.12 of tax for a $54.11 total. Backward is the one people get wrong: a $100.00 receipt total at 8.25% contains $7.62 of tax — not $8.25 — because the tax was charged on the $92.38 pre-tax price, not on the total. Expense reports, budgeting, and VAT-inclusive price tags all need the backward direction. Every figure is computed by the same tested engine as the calculator above, so the numbers in this copy cannot drift from the tool.
The two modes are a single relationship read in two directions. A price p taxed at a rate r becomes a total t = p × (1 + r/100); the tax is the difference, p × r/100. Give the tool the price and the rate and it returns the total and the tax; give it the total and the rate and it rearranges the same equation to recover the price. Nothing else is modeled — there is no rounding to a jurisdiction's rule, no table of rates, and no second tax stacked on the first. The rate you enter is the rate applied, exactly. For the income-tax side of a paycheck the mechanism is different; the guide How Tax Brackets Actually Work walks through it, and the full set of explainers is on the guides page.
The reverse mode is division, not subtraction
The single most common manual error with a receipt is to take the rate off the total: see a total and a rate, subtract that percentage of the total, and call the rest the pre-tax price. That removes too much, because the rate was never applied to the total — it was applied to the smaller pre-tax price. The engine instead divides: the pre-tax price is the total ÷ (1 + the rate), and the tax is what remains. Division undoes the multiplication that produced the total; subtraction does not.
The gap is easy to see on a worked figure. Take a $215.75 total at an illustrative 7.5% rate (illustrative only — not any jurisdiction's rate). Dividing, the pre-tax price is $200.70 and the tax inside is $15.05. Subtracting 7.5% of the total instead gives $16.18 of "tax" — $1.13 too much — and a correspondingly understated price. The larger the rate, the larger the error, which is why the backward direction exists as its own mode rather than a mental shortcut. When you need the tax embedded in a figure that already includes it, this is the mode to use.
A forward walk-through, line by line
Forward mode is the checkout direction: a known price, a known rate, and the tax added on top. Because the tool applies one flat rate to one amount, a cart of items at the same rate is just the sum of its lines. Here are three fictional prices taxed at an illustrative 6.5% (again, not any jurisdiction's rate), each line computed by the engine at build time:
| Price before tax | Tax at 6.5% | Total |
|---|---|---|
| $12.49 | $0.81 | $13.30 |
| $59.00 | $3.84 | $62.84 |
| $149.95 | $9.75 | $159.70 |
| Combined | $221.44 | $235.83 |
The three pre-tax prices sum to $221.44; the tax on them is $14.39, for a $235.83 total. Note that taxing each line and adding is identical to taxing the combined pre-tax amount once, because a flat rate distributes across a sum — $221.44 × 6.5% is the same $14.39. That identity only holds while a single rate applies to every line; the moment two items carry different rates, each group has to be run on its own and the results added, which the tool supports by computing one amount at a time.
Why the rate is yours to enter
The calculator asks for the rate because it deliberately keeps none. Sales tax in the United States is assembled from layers — a state rate, county and city additions, and special-district levies can stack into one combined rate — so the figure that applies to a purchase depends on where it happens, and those layers are set and revised by the authorities that impose them. Baking a rate table into a tool would mean shipping a snapshot that is wrong the moment any one of those layers changes, and wrong silently. Taking the rate from you avoids that: the one number most specific to your purchase is the one you supply, from a source you can check.
That is also why this page quotes no jurisdiction's rate and makes no claim about where any particular rate applies. The rates in the worked examples above are illustrative inputs chosen to show the arithmetic, nothing more. For the rate that actually applies to your purchase, the authoritative source is the one closest to the transaction — a recent receipt for the same location, or your state or local revenue authority's official rate lookup.
What the calculator accepts
Both fields run through one shared parser before the engine sees them. It strips dollar signs, grouping commas, percent signs, and spaces, then accepts a number; anything else — a stray letter, a second decimal point, a blank — is reported on the field rather than silently coerced into a result. The engine then applies its own rules and returns a typed error instead of a number when they fail, so no result is ever built from an input the tool could not make sense of.
The price or total must be greater than zero — a zero amount is refused with the message "The price must be greater than 0.", and a negative amount is refused as well, because a sale has no negative price. The rate must sit between 0% and 50%; a rate above that band is refused with "Enter a sales-tax rate between 0% and 50%.". A 0% rate is allowed and simply returns the amount unchanged with no tax, which is the honest answer for a tax-free purchase. Everything happens on your device as you type; nothing you enter is transmitted or stored.
What this calculator does not do
The tool is arithmetic on the rate you give it, and nothing more. It carries no table of jurisdictions and no opinion about which rate is correct, so it cannot tell you the rate for an address, cannot flag when a rate has changed, and cannot know whether a given item is taxable at all. Whether a particular item or category is taxed, and at what rate, is a matter of the rules where the sale happens — a question for your state or local revenue authority, not for a general calculator — and the tool takes no position on it. When items in a single cart would be taxed differently, the right approach is to compute each group at its own rate and add the results.
This site models US federal tax; sales tax is imposed by state and local authorities, so this page stays strictly on the arithmetic that is the same everywhere — add the rate, or extract it — and leaves the rate itself, and the question of what is taxable, to the authority that sets them. Treat the result as an exact computation of the rate you entered, not as a ruling on what rate or taxability applies to your purchase.
Frequently asked questions
What sales-tax rate should I enter?
The combined rate that applies to your purchase. This tool carries no jurisdiction data and holds no opinion about which rate is correct — it applies exactly the rate you type. Read the combined rate off a recent receipt for the same location, or look it up with your state or local revenue authority’s official rate tool, then enter it here and the arithmetic is exact for that rate.
How does the extract (reverse) mode work?
By dividing, not subtracting. A total that already includes r% tax equals the pre-tax price × (1 + r/100), so the pre-tax price is the total ÷ (1 + r/100) and the tax is whatever is left. That single division is the whole method, and the calculator runs it through the same tested engine as every worked figure on this page.
Why is subtracting the rate from the total wrong?
Because the rate was charged on the pre-tax price, not on the total. Subtracting r% of the total removes r% of a larger base than the tax was ever applied to, so it overstates the tax. On the worked example above — a $215.75 total at 7.5% — the tax inside is $15.05, while subtracting 7.5% of the total gives $16.18, overstated by $1.13.
What range of rates and amounts does the tool accept?
The price or total must be greater than zero, and the rate must be between 0% and 50%: a rate outside that band is refused with “Enter a sales-tax rate between 0% and 50%.”, and a zero amount with “The price must be greater than 0.”. Inputs may include dollar signs, grouping commas, a percent sign, and spaces — the parser strips them — and anything that is not a number is reported on the field rather than guessed at.
Can I use it on a tax-inclusive price tag?
Yes — that is exactly the extract mode. Any amount that already contains the tax, whether a receipt total or a price quoted tax-included, divides the same way: enter the tax-inclusive amount and the rate, and the tool returns the amount before tax and the tax embedded in it.
Does the calculator look up my rate for me?
No, by design. It has no table of jurisdictions and no way to know which rate your purchase carries, so rather than risk a figure that may be out of date it does the arithmetic precisely on the rate you supply. Verify the rate once — from a recent receipt or your revenue authority’s official lookup — and the result is exact for that rate.
Are all items taxed at the same rate?
Not necessarily. Whether a particular item or category is taxed, and at what rate, is a question for your state or local revenue authority, and this tool takes no position on it. The calculator applies one rate to one amount; when items in the same cart are taxed differently, compute each group separately and add the results.
Is my data sent anywhere, and is this federal or state tax?
Nothing you enter is transmitted — the calculation runs entirely in your browser. As for scope: this site models US federal tax, while sales tax is levied by state and local authorities, which is why this page does the arithmetic on the rate you provide rather than modeling any jurisdiction’s rules.
Not tax advice: rates and taxability vary by jurisdiction and product category — confirm the applicable rate with your state or local revenue authority. Values are processed locally in your browser and never transmitted. See the methodology page.