Sales Tax by Amount Calculator

About this calculator

Adding sales tax is a two-step calculation: tax amount = price × tax rate, then total = price + tax amount. It sounds trivial, but U.S. sales tax rates are set locally and stack — a combined state, county, and city rate can range from 0% in Oregon or Montana to over 10% in parts of California, Louisiana, or Illinois — so the "right" rate depends entirely on where the sale happens.

Retail cashiers, online sellers configuring checkout rules, and shoppers estimating a final receipt total all use this same calculation. Bookkeepers also run it in reverse to verify that a posted tax line matches the rate that should have applied to a given transaction.