Updated June 17, 2026
Know your ZIP? Skip the math
Type in a ZIP code and a dollar amount and this does the multiplication above for you.
The sales tax formula is: Tax = Price x Rate. Convert the percentage to a decimal by dividing by 100, multiply by the price, and add the result to the original price. Example: $80 at a 7.5% rate gives $80 x 0.075 = $6.00 in tax, for a total of $86.00.
Step-by-step calculation
- Find the combined rate for your location (state + county + city). Use the ZIP code calculator for an estimate.
- Divide the rate by 100 to get the decimal form. 8.25% becomes 0.0825.
- Multiply the pre-tax price by the decimal. $100 x 0.0825 = $8.25.
- Add to the price: $100 + $8.25 = $108.25 total.
Quick reference by common rates
| Rate | Tax on $50 | Tax on $100 | Tax on $500 |
|---|---|---|---|
| 6% | $3.00 | $6.00 | $30.00 |
| 7% | $3.50 | $7.00 | $35.00 |
| 8% | $4.00 | $8.00 | $40.00 |
| 9% | $4.50 | $9.00 | $45.00 |
| 10% | $5.00 | $10.00 | $50.00 |
How to reverse-calculate tax from a total
If you have the total and want the pre-tax price, divide by (1 + rate). A $108.25 total at 8.25% works out to $108.25 / 1.0825 = $100.00 pre-tax, so the tax was $8.25.
Things to know before you trust this number
The rate you pay is almost always a combined figure: a state base rate plus county and sometimes city taxes. A customer in unincorporated county territory can pay a different rate than someone inside city limits, even buying the same item at the same store. That is why a ZIP code lookup gives you an average rather than a guaranteed rate.
What the calculator does differently
Most people want a quick estimate, not an audit-ready figure. The calculator gives the average combined rate for a ZIP code. Before filing or remitting, confirm the exact rate with your state or local tax authority.
Know your ZIP? Skip the math
Type in a ZIP code and a dollar amount and this does the multiplication above for you.