Discount calculations come up constantly in retail, negotiation, and everyday shopping. A percentage discount means the price is reduced by that fraction of the original. A 30% off sale takes a £80 item to £56 — a saving of £24.
This calculator also helps with reverse discount problems: if you know the sale price and want to find what it was originally, or if you want to find what percentage off a price represents.
When comparing discounts across different original prices, percentage discounts can be misleading. A 50% discount on a £10 item saves £5. A 20% discount on a £50 item saves £10. The absolute saving matters as much as the percentage.
How to use the Discount Calculator
1
Enter the original price
2
Enter the discount percentage — e.g. 20 for 20% off
3
Tap Calculate — see the saving and the final price
Sale price at common discounts
What you pay after 10%, 20%, 25% and 50% off some common prices. To work out the discount on any amount, use the calculator above.
Price
10% off
20% off
25% off
50% off
£20
£18.00
£16.00
£15.00
£10.00
£50
£45.00
£40.00
£37.50
£25.00
£100
£90.00
£80.00
£75.00
£50.00
£200
£180.00
£160.00
£150.00
£100.00
Frequently Asked Questions
Enter the original price and 30 in the discount field.
Divide the discounted price by (1 − discount/100). E.g. £70 at 30% off → £70 ÷ 0.70 = £100 original.
Yes — two 20% discounts = 36% total off, not 40%. Calculate each one from the result of the previous.
Multiply the original price by 0.70 (100% − 30%) directly. Example: £120 × 0.70 = £84 sale price. Alternatively, find 30% of the price (£120 × 0.30 = £36) and subtract: £120 − £36 = £84. Both methods give the same result.
You pay full price for the first item and half price for the second. On two items at £20 each (total £40 normally), BOGOF50 costs £30 — a 25% overall saving, not 50%. True BOGOF (buy one get one free) gives 50% off two items.
Two sequential discounts are not simply added. A 20% discount followed by a 10% discount gives 28% total off — not 30%. Apply each to the running price: £100 → £80 after 20% off → £72 after 10% off. Combined saving: £28 (28%). The formula: combined = 1 − (1−d₁)(1−d₂).
Multiply the price by (1 minus the discount as a decimal). For example, 25% off £80 is £80 × 0.75 = £60. The calculator does this for you.
Subtract the sale price from the original, divide by the original, then multiply by 100. For example (£80−£60)÷£80×100 = 25% off.