Stacked discounts multiply, they do not add: an extra 10% off an already-20%-off price gives 28% total, not 30%. Enter the price and discounts to see the real final amount.
The second discount applies to the already-reduced price — that is why "extra X% off sale items" saves less than it sounds. The calculator shows the effective single-discount equivalent so you can compare offers honestly.
The effective single rate is what makes offers comparable: 20% then 10% is 28%, a flat 25% beats both, and 30% then 5% is 33.5%. Working out the equivalent single discount takes one multiplication and settles the question that stacked percentages exist to make difficult.
Order does not change the arithmetic — 20% then 10% and 10% then 20% both leave 72% of the price — but it can change the till. When a fixed-amount voucher is combined with a percentage, applying the percentage first leaves a smaller base for the voucher to come off, and stores differ on which they do.
Percentage-off and amount-off are not interchangeable either. A €20 voucher on a €40 item is 50% off; on a €200 item it is 10%. Where a store offers a choice between the two, the crossover point is simply the price at which the voucher equals the percentage — below it take the cash, above it take the percentage.
Frequently asked questions
How do stacked discounts combine?
They multiply on the successively reduced price: 20% then 10% leaves 0.8 × 0.9 = 72% of the price — a 28% total discount, not 30%.
Why isn't 20% plus 10% equal to 30% off?
Because the second discount applies to the already-reduced amount, so it removes less in absolute terms. The gap widens as the percentages grow.
How do I calculate a sale price?
Multiply the original price by one minus the discount: €80 at 25% off is 80 × 0.75 = €60. The calculator also shows the effective single discount of stacked offers.