Sales Tax Calculator
Add tax to a price or back the tax out of a total. Enter the combined rate for the exact location of the sale. Select a mode below.
Add Tax
Pre-tax price + tax rate
Remove Tax
Total with tax + tax rate
Quick Examples
What Is a Sales Tax Calculator?
A sales tax calculator moves between a pre-tax price and an after-tax total. In Add Tax mode, enter the price before tax and the tax rate to get the tax amount and the total. In Remove Tax mode, enter a tax-inclusive total and the rate to back out the pre-tax price and the tax hidden inside it.
In the United States there is no national sales tax — the rate is set by the state, county, city, and special districts where the sale happens, and those layers stack into one combined rate. That is why this tool asks you to enter the rate rather than guessing it. This page covers the formulas, how combined rates work, worked examples in both directions, common mistakes, key terms, and frequently asked questions.
Sales Tax Formulas
Adding tax is a percentage increase; removing it is the reverse operation. Here rate is the combined rate written as a decimal (8.25% = 0.0825):
The reverse formula divides because the tax was charged on the pre-tax price, not the total: 108.25 / 1.0825 = $100.00 pre-tax and $8.25 tax. Subtracting 8.25% of the total instead gives $8.93 — too high.
How to Use This Sales Tax Calculator
- Pick a mode. Add Tax for a pre-tax price, Remove Tax for a receipt total.
- Enter the amount. The listed price, or the amount actually paid including tax.
- Enter the combined rate. The full state-plus-local rate as a percentage, such as 8.25 — for the store's city and county, not just the state.
- Press Calculate. The tool shows the tax amount, the pre-tax price, and the total.
How Combined State and Local Rates Work
The US has no single sales tax rate: the state sets a base rate, and counties, cities, and special districts each add their own slice. What you pay at the register is the sum of every layer that applies at the store's exact address.
Five states levy no statewide general sales tax: Alaska, Delaware, Montana, New Hampshire, and Oregon (some Alaskan localities add local tax). Elsewhere, state base rates run 2.9% (Colorado) to 7.25% (California), with local taxes adding several more points in many cities.
Rates drift over time as district taxes expire or renew, so no online calculator can keep a live table for every US tax jurisdiction — which is why this tool leaves the rate as an input you control. For the official combined rate at a specific address, check your state Department of Revenue.
Worked Examples
Example 1 (Add Tax): $100 Item at an 8.25% Combined Rate
- Tax = 100 x (8.25 / 100) = 100 x 0.0825 = $8.25
- Total = 100 + 8.25 = $108.25
- One-step check: 100 x 1.0825 = $108.25
Example 2 (Add Tax): $26.99 Item at 6%
- Tax = 26.99 x 0.06 = $1.62 (rounded from $1.6194)
- Total = 26.99 + 1.62 = $28.61
Example 3 (Add Tax): Budgeting a $28,000 Car at 9%
- Tax = 28,000 x 0.09 = $2,520.00
- Total = 28,000 + 2,520 = $30,520.00
The same car at 7% instead of 9% saves $560 in tax — a few points is real money on big-ticket purchases.
Example 4 (Remove Tax): $53.50 Receipt Total at 7%
- Pre-tax price = 53.50 / 1.07 = $50.00
- Tax included = 53.50 - 50.00 = $3.50
Notice that simply taking 7% of $53.50 gives $3.745 — too high — because the tax was charged on $50.00, not on the full $53.50. This is the single most common error when separating tax out of a total, and it is exactly why the reverse mode divides instead of subtracting.
Sales Tax Quick-Reference Table
Total including tax for typical price points at common combined rates:
| Price | + 5% | + 6% | + 7% | + 8.25% | + 10% |
|---|---|---|---|---|---|
| $10.00 | $10.50 | $10.60 | $10.70 | $10.83 | $11.00 |
| $10.49 | $11.01 | $11.12 | $11.22 | $11.36 | $11.54 |
| $26.99 | $28.34 | $28.61 | $28.88 | $29.22 | $29.69 |
| $50.00 | $52.50 | $53.00 | $53.50 | $54.13 | $55.00 |
| $100.00 | $105.00 | $106.00 | $107.00 | $108.25 | $110.00 |
Common Sales Tax Mistakes
- Entering only the state rate. Typing 6.25% when the real combined rate is 8.25% is the most common cause of a wrong total.
- Subtracting the percentage to remove tax. Removing 8.25% from a $108.25 total by multiplication gives $8.93 of "tax" — $0.68 too much. Divide by (1 + rate) instead.
- Using the wrong location's rate. In-store purchases use the store's location; shipped goods often use the delivery address.
- Taxing exempt items. Groceries and prescriptions may be exempt or reduced-rate — run mixed baskets as separate calculations.
- Rounding the rate early. Enter the full rate (8.375%, not 8.4%); registers round the computed tax to the nearest cent.
- Adding tax before the discount. At most registers the discount comes first and tax applies to the reduced price.
Key Terms
- Combined rate: the single percentage actually charged — state rate plus any county, city, and special-district rates at the point of sale.
- Pre-tax price (taxable amount): the price the tax is calculated on, before tax is added.
- Total (gross): the pre-tax price plus the tax — what you actually hand over.
- VAT (value-added tax): the consumption tax used in most countries outside the US; unlike US sales tax, it is usually already included in the displayed price.
Frequently Asked Questions
Related Calculators
Related percentage tools:
- Discount Calculator: find the sale price first, then add tax on top for the true checkout total.
- Percentage Calculator: all four percentage problem types, including percentage change.
- Tip Calculator: work out gratuity on the pre-tax subtotal and split the bill.
- Simple Interest Calculator: flat percentage rates applied once per period.
- Compound Interest Calculator: percentage growth compounded over multiple periods.
- Loan EMI Calculator: monthly payments on financed purchases, where tax affects the amount borrowed.
Conclusion
Sales tax math: Tax = Price x (Rate / 100), Total = Price x (1 + Rate / 100). To undo it, divide the total by (1 + Rate / 100). Always enter the combined state-plus-local rate for the sale's exact location — the state base rate alone is almost never what the register charges.
Watch for the common traps — the wrong mode, exempt items, early rounding, and taxing before the discount — and use the calculator above for instant results in both directions.