Guide

How to Calculate a Discount and the Final Sale Price

Learn the discount formula, how to work backwards from a sale price, and how to spot misleading discounts.

A discount calculator works out the sale price after a percentage discount, the amount you save, or the original price before a discount. It takes the mental maths out of shopping.

The discount formula

Sale price = Original × (1 − Discount% ÷ 100)

Savings = Original × (Discount% ÷ 100)

To work backwards from a sale price when you know the discount percent: Original = Sale price ÷ (1 − Discount% ÷ 100).

How to use the calculator

  1. Enter the original price and the discount percentage to see the sale price and savings.
  2. Or enter the sale price and discount to recover the original price.
  3. Stack discounts by applying one, then the other — they do not simply add.

Examples

A $120 jacket at 30% off: savings = 120 × 0.30 = $36; sale price = $84. Two stacked discounts of 20% and 10% on $100: 100 × 0.80 = $80, then 80 × 0.90 = $72 — not a 30% discount ($70).

When a discount calculator is useful

  • Comparing sale prices across stores.
  • Checking whether a "was/now" deal is as good as it looks.
  • Calculating bulk or trade discounts.
  • Working out the original price from a sale tag.

Spotting misleading discounts

Some retailers inflate the "was" price to make the discount look bigger. Use the reverse calculation to check whether the original price is plausible. Stacked discounts compound, so "20% off, then another 20% off" equals 36% off total, not 40%.

Put it into practice

Use the Discount Calculator right now — free, in your browser, no sign-up required.

Try the Discount Calculator