How to Calculate Sales Tax — Formula, Examples & State Rates

To calculate sales tax, multiply the pre-tax price by the tax rate: an $80 item at 8% tax costs $80 × 0.08 = $6.40 in tax, for a total of $86.40. The only two things you ever need are the taxable price and the combined rate where the sale happens — state rate plus county, city and district rates, which is why the same item is taxed differently in different towns. This guide walks through the formula, combined rates, what is exempt, and how to work backwards from a total that already includes tax.

Key takeaways

Formula: tax = price × rate · total = price × (1 + rate). Always convert the percentage to a decimal first (8.25% → 0.0825).
Your real rate is the combined rate at the delivery address — state + county + city + district. The U.S. average combined rate is 7.53% (Tax Foundation, July 2026).
Tax applies only to taxable items — groceries, prescription medicine and clothing are exempt or reduced in many states.
Backwards: pre-tax price = total ÷ (1 + rate). Never subtract the percentage from the total — that is the most common sales tax mistake there is.
Five states have no statewide sales tax (NH, OR, MT, AK, DE) — but Alaska localities can charge their own.

The Sales Tax Formula

Sales tax = pre-tax price × tax rate (as a decimal)

Total price = pre-tax price + tax — or in one step, price × (1 + rate)

Step by step:

Convert the rate to a decimal. Move the decimal point two places left: 8% → 0.08, 7.25% → 0.0725, 8.875% → 0.08875.
Multiply the price by the decimal. That is your tax amount.
Add it to the price for the total — or skip step 3 by multiplying the price by (1 + rate) instead.

Example: An $80 jacket at 8%:

Tax: $80 × 0.08 = $6.40
Total: $80 + $6.40 = $86.40 (one-step check: $80 × 1.08 = $86.40 ✓)

Worked Example With a Real Combined Rate

Most real purchases are not taxed at a tidy 8%. In Austin, Texas, the combined rate is 8.25% — the state’s 6.25% plus 1% city and 1% transit district tax.

A $50 item in Austin:

Tax: $50 × 0.0825 = $4.125 → rounds to $4.13
Total: $54.13

Note the rounding: sales tax is worked out on the full taxable amount and rounded to the nearest cent, which is why your receipt occasionally differs by a penny from a rough mental estimate.

Taxing a Mixed Basket: Exempt Items Don’t Count

Sales tax is charged on the taxable subtotal only. If part of a purchase is exempt — groceries in most states, for example — that part passes through untaxed.

Example (8% rate): $80 of taxable goods plus $50 of exempt groceries:

Tax applies to $80 only: $80 × 0.08 = $6.40
Total: $80 + $50 + $6.40 = $136.40

One related rule: store discounts and coupons reduce the price before tax — you are taxed on what you actually pay, not the ticket price. (Manufacturer coupons are treated differently in some states.)

Why Your Rate Is Higher Than Your State’s Rate

The rate on a state website is only the first layer. Most addresses stack up to four:

Combined rate = state + county + city + special district (transit, stadium, etc.)

Texas: 6.25% state, with local jurisdictions allowed up to 2% more — maximum combined 8.25%.
California: 7.25% statewide (the highest state rate in the country), plus district taxes that can push combined rates to about 11.25% in the highest-tax cities.
New York: only 4% state — but counties and cities add 3–4.875%, plus a 0.375% surcharge in the New York City metro district, making NYC’s combined rate 8.875%.
Chicago: 10.25% combined.

Because district boundaries are drawn independently, they do not follow ZIP codes — two addresses in the same ZIP, even on the same street, can owe different rates. When the exact rate matters, look it up by street address on your state revenue department’s website, not by ZIP.

How high does it get? The average combined rate nationwide is 7.53%, but Louisiana’s average combined rate is 10.13% and Tennessee’s is 9.61% (Tax Foundation, July 2026) — and individual cities go higher still.

Sales Tax Rates by State (The Short Version)

State	State rate	What to add
California	7.25%	District taxes — combined up to ~11.25%
Texas	6.25%	Local up to 2% — max combined 8.25%
Florida	6.00%	County surtax of 0–2%
New York	4.00%	Local 3–4.875% + 0.375% in the NYC metro area

States with no statewide sales tax: New Hampshire, Oregon, Montana, Alaska and Delaware. The catch: Alaska allows its localities to levy sales tax (average combined rate 1.82%), so “no sales tax” is only completely true in the other four.

Rates change — usually at the start of a quarter — so treat any table (including this one) as a starting point and confirm your rate with your state revenue department.

What Is (and Isn’t) Taxed

Exemptions are where calculations most often go wrong. The big three:

Groceries: food for home consumption is exempt in many states (Texas and Florida among them) or taxed at a reduced rate — but prepared food, hot food, candy and soda are usually taxable even there.
Prescription medicine: exempt in nearly every state (California and New York included, where even over-the-counter medicine is exempt in New York).
Clothing: fully exempt in Pennsylvania, New Jersey, Minnesota and Vermont. New York exempts clothing and footwear under $110 per item from its state tax — buy a $100 coat in New York City and the sales tax on it is $0, a fact even some major tax guides get wrong.

Services, digital products and shipping all have their own rules that vary by state — shipping, for instance, is taxed on taxable goods in Ohio but exempt in Virginia when stated separately on the invoice. When in doubt, your state revenue department’s guidance for your exact item is the source of truth.

How to Calculate Sales Tax Backwards From a Total

Sometimes you only have the final, tax-included total — a receipt, a day’s card takings — and need the pre-tax price back out of it. The formulas reverse:

Pre-tax price = total ÷ (1 + rate)

Tax amount = total − pre-tax price

Example: A receipt totals $108 and the rate is 8%:

Pre-tax price: $108 ÷ 1.08 = $100
Tax: $108 − $100 = $8 ✓ (check forwards: $100 × 0.08 = $8)

The mistake almost everyone makes

Do not subtract the percentage from the total. Tax was calculated on the pre-tax price, so it is a smaller percentage of the total. On that same $108 receipt, subtracting “8% of $108” removes $8.64 and leaves $99.36 — the wrong price, and $0.64 of tax that never existed. On $1,080 of daily takings the same error invents $6.40 of phantom tax and understates your sales by the same amount. The divisor is always (1 + rate) — never the rate alone, and never subtraction.

Two more backwards-calculation traps:

Mixed receipts: if part of the receipt was exempt (groceries, medicine), subtract those items first, then divide what remains. Running the formula on the whole receipt invents tax on items that were never taxed.
The missing penny: receipts are rounded to the cent at the register, so a backwards calculation can land 1¢ off. That is rounding, not an error.

For receipts and takings of any size, our free Reverse Sales Tax Calculator does the division for you — enter the total and the rate, and it returns the pre-tax price and the exact tax amount.

Common Sales Tax Mistakes

Using only the state rate. In most metro areas that undercharges by 1–5 points — and a seller who under-collects pays the difference out of pocket at filing time.
Subtracting the percentage to go backwards. Covered above — always divide by (1 + rate).
Taxing the ticket price instead of the paid price. Store discounts come off before tax.
Taxing exempt items — or running backwards maths on a receipt that includes them.
Multiplying by the percentage itself. 8% is 0.08, not 8. If your “tax” is bigger than the item, this is why.
Using a stale rate, or the wrong location’s rate. Rates change quarterly, and the rate that applies is generally the one where the buyer receives the goods — not your shop’s address, and not a ZIP-code average.

Frequently Asked Questions

What is the formula for sales tax?

Tax = pre-tax price × rate (with the rate as a decimal), and total = price × (1 + rate). An $80 item at 8%: $6.40 tax, $86.40 total.

How do I calculate sales tax backwards from a total?

Divide the total by (1 + rate) to get the pre-tax price, then subtract to find the tax. A $108 total at 8% is $100 + $8 tax. Never subtract the percentage from the total.

How do I find the sales tax rate for an address?

Add the state, county, city and district rates for the exact street address. ZIP codes are unreliable because district boundaries cross them; every state revenue department offers a free address-based rate lookup.

What is the average sales tax in the US?

The average combined state-and-local rate is 7.53% (Tax Foundation, July 2026). State base rates run from 0% to 7.25%, and average combined rates from 1.82% in Alaska (local taxes only) to 10.13% in Louisiana.

Which states have no sales tax?

New Hampshire, Oregon, Montana, Alaska and Delaware have no statewide sales tax. Alaska is the exception within the exception — its localities can and do charge local sales tax.

Is there sales tax on groceries, clothing and medicine?

Groceries are exempt or reduced-rate in most states (prepared food usually is not). Prescription medicine is exempt in nearly all states. Clothing is fully exempt in Pennsylvania, New Jersey, Minnesota and Vermont, and exempt under $110 per item (state tax) in New York.

The Bottom Line

Sales tax maths is two multiplications: price × rate for the tax, price × (1 + rate) for the total. Everything else is using the right rate (the combined rate at the delivery address), taxing only what is taxable, and — when you have to work backwards from a total — dividing by (1 + rate) instead of subtracting. For that last job, the Reverse Sales Tax Calculator gives you the pre-tax price and tax amount instantly.

Rates verified November 2026 against the Tax Foundation’s 2026 midyear rate update, the California CDTFA, the Texas Comptroller, the Florida Department of Revenue and the New York Department of Taxation and Finance. Sales tax rates change frequently — confirm yours with your state revenue department.