Sales Tax Calculator

Sales tax is a simple surcharge: you take the pre-tax price, multiply it by the tax rate expressed as a decimal, and add the result back on. Because the tax is a fixed percentage of the price, a higher-priced item carries proportionally more tax, but the rate itself never changes with the amount.

The forward direction — adding tax to a known price — is the everyday case at a checkout. The reverse direction matters when a price is quoted tax-inclusive and you need to know the underlying amount, for example to record the net figure on an expense report or invoice. To go backwards you divide the inclusive total by (1 + rate ÷ 100). Dividing rather than simply subtracting the percentage is the step most people get wrong: subtracting the rate from the total understates the original price, because the tax was charged on the smaller pre-tax base, not on the larger total.

The formula is currency-agnostic. Switch the currency at the top of the page to read your numbers in whatever currency you use; the arithmetic is identical everywhere.

Take a 100 pre-tax purchase at an 8% sales tax rate. The tax is 100 × 0.08 = 8, so the total with tax is 108. Now reverse it: if you were handed a 108 tax-inclusive total and wanted the pre-tax price, you would divide by 1.08 — giving 100 back, exactly the figure you started from. Notice that simply subtracting 8% of 108 would have left 99.36, which is wrong, because the tax was never charged on the full 108.

Rates often combine several layers — a state or national rate plus a local or city rate — so enter the combined effective rate for an accurate total. Some categories (groceries, medicine, certain services) may be taxed at a reduced rate or exempt entirely; in those cases use the rate that actually applies. Rounding can also cause a one-unit discrepancy versus a receipt, since some sellers round the tax on each line item rather than on the order total.