Sales tax calculator
Enter an amount and a ZIP code — the combined state, county, city and special-district rate fills in automatically. Switch to reverse mode to back tax out of a total.
Quick answer
Sales tax = price × rate. At 8.25%, a $100 purchase is $8.25 tax and $108.25 total. Use the ZIP field so you never have to guess the local rate.
Sales tax calculator
Enter a pre-tax amount to see the tax due in United States.
Type a 5-digit ZIP and the combined rate below fills in automatically.
- Pre-tax
- $100
- Sales tax at 8.25%
- $8.25
- Total
- $108.25
Tax is rounded to the nearest cent on the full transaction, which is how most registers compute it. Line-item rounding can differ by a cent or two on long receipts.
Questions people ask
Common questions about sales tax math.
How do I calculate sales tax on a purchase?
Multiply the pre-tax price by the combined rate as a decimal, then add it back. On $100 at 8.25%, the tax is $8.25 and the total is $108.25.
How does the ZIP code lookup work?
Type a 5-digit ZIP and the calculator fills in the published combined state, county, city and district rate for that area, so you do not have to know the rate yourself.
Why is my receipt a cent off?
Retail systems round tax per line item or per bracket, while this tool rounds once on the order subtotal. Differences of one or two cents on multi-item receipts are normal.
Remove sales tax from a total instead
Sources & transparency
- State departments of revenue — published combined rates behind the ZIP lookup
Last reviewed August 2026. Figures are published for reference and can change; verify with the source agency before filing or contracting. How we build and check this data.