Discount Calculator
The formula
Sale price = original price × (1 − discount ÷ 100), and the saving is the original price minus the sale price.
Example: a €120 jacket at 30% off costs 120 × 0.70 = €84, a saving of €36.
Stacked discounts don't add up
When a shop offers "an extra 20% off sale prices", the second discount applies to the already-reduced price:
- 30% then 20%: 120 × 0.70 × 0.80 = €67.20, a total discount of 44%, not 50%.
- 20% then 10%: × 0.80 × 0.90 = × 0.72, a total discount of 28%, not 30%.
The order doesn't matter: 20% then 30% gives the same final price as 30% then 20%.
The reverse calculation
If you know the sale price and the percentage, divide to find the original price: original = sale price ÷ (1 − discount ÷ 100). A €64 item at 20% off was originally 64 ÷ 0.80 = €80. Note that it is not 64 + 20%: that would give €76.80.
Checking a deal
- Reference price: in the EU, a shop announcing a price reduction must use as reference the lowest price it charged in the previous 30 days. This rule, introduced in 2022, prevents inflating a price just before a sale.
- Price per unit: for groceries, compare the price per kilo or per litre shown on the shelf label — a "−30% on the second item" offer is really 15% off if you buy two.
- Total cost: shipping fees, delivery charges or a subscription can cancel out the saving.
Use the percentage decrease calculator to find the discount rate between two prices you already know, for example €80 to €64 (20%).
Frequently Asked Questions
How do I calculate 25% off?
Multiply the price by 0.75. For example, 25% off €60 is 60 × 0.75 = €45, a saving of €15.
Is 20% + 10% the same as 30% off?
No. Successive discounts multiply: 0.80 × 0.90 = 0.72, which is 28% off in total.
How do I find the original price from the sale price?
Divide the sale price by (1 − discount). A €64 price after 20% off was originally 64 ÷ 0.8 = €80.