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Enter a price and tax rate to add tax or extract the pre-tax amount instantly.
How Sales Tax Works
Two operations — add tax to a price, or strip tax out of a total. Both use the same multiplier: (1 + Rate ÷ 100).
What Is Sales Tax and How Is It Calculated?
Sales tax is a percentage of a purchase price levied by state and local governments at the point of sale. Unlike income tax or property tax, it is charged per transaction — the retailer collects it from the buyer and remits it to the government. In the United States, there is no federal sales tax; rates vary by state from 0% in five states up to a combined state-plus-local rate above 10% in some counties. The base formula is simple: multiply the pre-tax price by the tax rate expressed as a decimal, then add the result to the original price.
How to Add Sales Tax to a Price
To add sales tax to a pre-tax price, multiply the price by (1 + rate ÷ 100). This combines the original price and the tax charge in a single step. Alternatively, calculate the tax amount separately — price × (rate ÷ 100) — and add it to the original price.
Example: a $49.99 item with 7% sales tax. Tax amount = $49.99 × 0.07 = $3.50 (rounded). Total = $49.99 + $3.50 = $53.49. You can verify: $49.99 × 1.07 = $53.49. Real-world uses include budgeting before checkout, online price comparison across regions, and calculating the true cost of a purchase when the listed price is tax-exclusive.
How to Reverse Sales Tax (Find the Pre-Tax Price)
When you have a tax-inclusive total and want to find the original price before tax, divide the total by (1 + rate ÷ 100). This is the reverse of the add-tax formula and it works because the total equals the pre-tax price multiplied by that same factor.
Example: a receipt shows $53.49 in a 7% tax region. Pre-tax = $53.49 ÷ 1.07 = $49.99. Tax collected = $53.49 − $49.99 = $3.50. Common use cases include expense reports where you need to separate the net cost from the tax component, price comparisons when one price includes tax and another does not, and VAT refund calculations when travelling.
A common mistake is to subtract the percentage directly — subtracting 7% from $53.49 gives $49.75, which is wrong. You must always divide by (1 + rate ÷ 100), not subtract (rate ÷ 100).
Sales Tax Rates by State — Quick Reference
State base rates combined with average local rates. Rates change frequently and vary by county and city — verify with your state revenue department before filing.
| State | Approx. Combined Rate |
|---|---|
| California | 8.68% |
| Texas | 8.20% |
| New York | 8.52% |
| Florida | 7.07% |
| Illinois | 8.82% |
| Washington | 9.38% |
| Colorado | 7.77% |
| Georgia | 7.31% |
| Oregon | 0.00% (no sales tax) |
| Delaware | 0.00% (no sales tax) |
Sales Tax vs VAT — What Is the Difference?
US sales tax and European Value Added Tax (VAT) both apply a percentage rate to goods and services, but they work differently in practice. Sales tax is added on top of the advertised price at the point of sale — the shelf price is tax-exclusive and the register adds it. VAT is embedded in the displayed price — European prices are tax-inclusive, so what you see on the label is what you pay.
The maths, however, is identical. If a product costs £80 with 20% VAT included, the pre-VAT price is £80 ÷ 1.20 = £66.67, and the VAT component is £80 − £66.67 = £13.33. This is exactly what the Reverse Tax mode does. Whether you call it VAT, GST (Canada / Australia), or HST, the formula is the same — just enter the inclusive amount and the rate.
Sales Tax Calculator FAQ
What is the formula for sales tax?
To add tax: Total = Pre-Tax Price × (1 + Rate ÷ 100). To find the pre-tax price from a total: Pre-Tax = Total ÷ (1 + Rate ÷ 100). Tax amount in both cases = Total − Pre-Tax.
How do I add 8% tax to a price?
Multiply the price by 1.08. For example, $50.00 × 1.08 = $54.00. Alternatively, calculate 8% of $50.00 = $4.00, then add to get $54.00. Both approaches give the same result.
How do I find the original price before tax?
Divide the tax-inclusive total by (1 + rate ÷ 100). For a $54.00 total with 8% tax: $54.00 ÷ 1.08 = $50.00. Never subtract the percentage directly — that gives the wrong answer.
What is the difference between tax-exclusive and tax-inclusive pricing?
Tax-exclusive (the US norm) means the listed price does not include tax — it is added at checkout. Tax-inclusive (standard in Europe and Australia) means the listed price already includes the tax. Use Add Tax mode for tax-exclusive prices and Reverse Tax mode for tax-inclusive prices.
Why does my total not match when I multiply the tax rate myself?
Rounding. Tax amounts are typically rounded to the nearest cent after each multiplication. Different software rounds at different stages — some round the tax amount first, others round the total. This calculator rounds to two decimal places after computing the tax amount, which matches most retail systems. Small discrepancies of one cent are common and normal.
Can I use this calculator for VAT?
Yes. VAT and sales tax use the same maths. To add VAT, use Add Tax mode with the VAT rate. To strip VAT from a VAT-inclusive price (common in Europe), use Reverse Tax mode. Enter 20 for 20% UK VAT, 19 for German VAT, or whatever rate applies in your region.
What states have no sales tax?
Five US states have no statewide sales tax: Alaska, Delaware, Montana, New Hampshire, and Oregon. Note that Alaska allows local municipalities to levy their own sales taxes, so some Alaskan cities do charge a local rate even though there is no state-level tax.
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