Discount Calculator (with optional sales tax)

How discount math works

Discounted price = original × (1 − discount/100). A 20% discount on a $100 item leaves $80. Sales tax is applied to the discounted amount, not the original — so $80 × (1 + 8% tax/100) = $86.40 final.

The 'you save' amount is the discount in dollars: original × discount/100. For our $100 example at 20% off, you save $20. This is what shoppers naturally want to see — not just the percent.

Stacking discounts

Two discounts don't add. A '20% off' coupon on top of a '20% off sale' is 36% off total, not 40% — because the second discount applies to the already-reduced price (0.8 × 0.8 = 0.64 = 36% off the original).

To stack, run the calculator twice: first with the bigger discount, then plug the result back in as the new 'original' with the second discount. Or, if you have multiple coupons, multiply (1 − d1/100) × (1 − d2/100) × ... and subtract from 1 to get the total effective discount.

Tax timing varies by country

United States: sales tax is added at the register, after any discounts. Use this calculator's tax field directly. Each state and city has its own rate (NYC 8.875%, LA 9.5%, no tax in Oregon).

EU/UK: VAT is typically already in the displayed price, so don't double-count. Set tax to 0 if the price you entered is VAT-inclusive. Japan's consumption tax is also usually included in displayed prices (総額表示).

Sometimes shipping is taxable, sometimes not. This calculator assumes the price you enter is the taxable amount. For complete cart math, total your taxable items separately.