How to Calculate a Percentage Discount
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A discount is a percentage taken off a price. The quickest method is to multiply the price by what remains after the discount.
The basic calculation
Sale price = original price × (1 − discount ÷ 100). A price of 80 with 25% off is 80 × 0.75 = 60, so you save 20.
To work backwards, divide the sale price by the remaining fraction: 60 ÷ 0.75 = 80.
Two discounts in a row
Discounts do not add up when they are applied one after another. 20% off followed by another 10% off is 0.80 × 0.90 = 0.72, so the real discount is 28%, not 30%. The Discount Calculator has a field for a second discount for this reason.
Discounts and tax
Whether tax is calculated before or after the discount depends on the shop and the place. If you need the tax too, use the VAT Calculator on the discounted price.