Sales tax calculator

Start with the taxable amount

Tax = taxable base × rate ÷ 100. Total = taxable base + tax. Use the combined rate applicable to that transaction, rather than automatically adding unrelated state, local or special rates. If a discount, shipping charge or mixed basket changes the taxable base, establish that base first.

This is a user-entered-rate calculator. It contains no address lookup, jurisdiction database or taxability decision. It does not determine the tax a seller is legally required to collect.

An 80.00 purchase at a chosen 8%

Assume the entire 80.00 is taxable at an illustrative combined 8%. Tax is 80 × 0.08 = 6.40; checkout total is 86.40. If a total of 108.00 already includes the same 8%, its base is 108 ÷ 1.08 = 100.00 and included tax is 8.00.

These examples do not represent the rate of a particular location. If only part of the purchase is taxable, applying the rate to the whole basket overstates the result.

Similar arithmetic, different rules

Adding a percentage to a taxable base uses the same arithmetic as adding VAT. That does not make sales tax and VAT interchangeable legal systems. Registration, exemptions, collection, credits and reporting require the rules of the relevant jurisdiction.

For comparison with inclusive-price arithmetic, see GOV.UK: prices with and without VAT. For EU VAT rate variation, see European Commission: VAT rates. Neither source supplies a U.S. sales-tax rate; obtain that from the appropriate revenue authority.

A matching checkout percentage does not make two tax systems identical. Read how sales tax and VAT differ; if the known tax is already inside the price, the inclusive-price explanation shows why reversing it uses division.

Before comparing a receipt

Confirm that the rate and taxable subtotal refer to the same purchase date and location. Check whether the receipt rounds tax by line or total, treats particular items differently, or includes separate charges. Currency selection changes formatting, not the tax law or exchange rate.