Discount Calculator
Work out the sale price after a percentage discount and see exactly how much you save. Enter the original price and the discount — the maths is done for you.
The discount formula
Sale Price = Original Price × (1 − Discount ÷ 100)
- Divide the discount by 100 and subtract it from 1 to build a multiplier — 20% off becomes 0.8, meaning you pay 80% of the original price.
- Multiply the original price by that multiplier to get the sale price.
- Your saving is the original price minus the sale price: Saving = Original Price − Sale Price.
How to use this calculator
- Enter the original price in pounds.
- Enter the discount percentage — for example, 20 for 20% off.
- The sale price and your saving update instantly.
Worked examples
A simple percentage discount
A £45 item is marked 20% off. Multiplier = 1 − 20 ÷ 100 = 0.8. Sale price = £45 × 0.8 = £36. You save £45 − £36 = £9.
A larger discount
An £80 coat is reduced by 30%. Multiplier = 1 − 30 ÷ 100 = 0.7. Sale price = £80 × 0.7 = £56. You save £80 − £56 = £24.
Half price
A £120 printer is sold at 50% off. Multiplier = 1 − 50 ÷ 100 = 0.5. Sale price = £120 × 0.5 = £60. You save £60.
Stacked discounts are not additive
A £100 item has 20% off, then a further 10% off. First reduction: £100 × 0.8 = £80. Second reduction: £80 × 0.9 = £72. The total saving is £28 — not 30% off, because the second discount applies to the already-reduced price.
Working out the discount percentage from two prices
An item drops from £45 to £36. Discount % = (45 − 36) ÷ 45 × 100 = 20%. Use the percent off calculator to do this reverse calculation in one step.
Discount, markdown and percentage decrease
These terms describe price reductions. Here is how they relate.
- Discount
- A reduction applied to a price, usually expressed as a percentage. A 20% discount means the customer pays 80% of the original price.
- Markdown
- The same maths as a discount, but the term is more often used by retailers describing the reduction in stock value. A 20% markdown and a 20% discount produce the same sale price.
- Percentage decrease
- The general calculation behind any fall in value, not just prices. A 20% discount is a 20% decrease in price — use the percentage decrease calculator for non-price figures.