🏷️ Discount Calculator
Calculate the final price after any discount and see exactly how much you save.
Enter the price and discount
How to calculate a discount
Calculating a percentage discount is straightforward once you know the formula. To find the sale price after a percentage discount, multiply the original price by (1 − discount/100). For example, to calculate 20% off £89.99:
- Savings = £89.99 × 0.20 = £18.00
- Final price = £89.99 − £18.00 = £71.99
- Or directly: £89.99 × 0.80 = £71.99
Quick discount reference table
Here are the most common discount percentages and their multipliers — useful for mental maths when shopping:
| Discount | Multiplier | £100 becomes |
|---|---|---|
| 5% off | × 0.95 | £95.00 |
| 10% off | × 0.90 | £90.00 |
| 15% off | × 0.85 | £85.00 |
| 20% off | × 0.80 | £80.00 |
| 25% off | × 0.75 | £75.00 |
| 30% off | × 0.70 | £70.00 |
| 40% off | × 0.60 | £60.00 |
| 50% off | × 0.50 | £50.00 |
| 70% off | × 0.30 | £30.00 |
| 75% off | × 0.25 | £25.00 |
How to find the original price before a discount
If you know the sale price and the discount percentage but need to find the original price, divide the sale price by (1 − discount/100). For example, if an item costs £80 after a 20% discount, the original price was £80 ÷ 0.80 = £100.
Tips for shopping sales and avoiding discount traps
- Check the original price: Some retailers inflate prices before a sale. Check price history tools to verify the original price was genuine.
- Compare per unit: A larger pack at a lower percentage discount may be cheaper per unit than a smaller pack with a bigger discount.
- Stack discounts carefully: If you apply a 20% discount code on top of a 30% sale, you don't get 50% off. You get 30% off, then 20% off the reduced price — which equals 44% total.
- VAT and tax: In the UK and EU, displayed prices include VAT. In the USA, sales tax is added at checkout — always check whether the discount applies before or after tax.