Sales Tax Calculator

Sales Tax Calculator

Calculate sales tax, after-tax price and reverse a tax-inclusive total.

UNDERSTAND THE ANSWER

How is this calculated?

The calculator multiplies unit price by quantity, applies the percentage tax to that subtotal and adds the tax to get the final total.

Sales tax formulaTax = Pre-tax subtotal × Tax rate ÷ 100

A practical example

A $100 purchase taxed at 6.5% has $6.50 in sales tax and costs $106.50 after tax.

Assumptions, interpretation and common mistakes

Calculation assumptions

  • One combined percentage tax rate applies to the entire pre-tax subtotal.
  • Every entered item is taxable at the same rate.
  • Tax is calculated before any jurisdiction-specific rounding rule.

How to interpret the result

  • Pre-tax subtotal is unit price times quantity.
  • Sales tax is the added tax amount, not the tax-inclusive price.
  • The final total is the estimated amount paid after tax.

Common mistakes to avoid

  • Entering a 6.5% rate as 0.065 instead of 6.5.
  • Ignoring local or product-specific exemptions and surtaxes.
  • Applying tax before a discount when local rules tax the discounted price.