How to calculate two successive discounts
Calculate stacked discounts correctly and understand why 20% off followed by 10% off is a total discount of 28%, not 30%.
Updated · How we checkApply each discount to the remaining price after the previous discount.
Turn a discount into a price multiplier
A discount of d percent leaves the multiplier 1 − d ÷ 100. Multiply the original price by this factor to find the reduced price. A 20% discount therefore leaves 80% of the original price.
Multiply the remaining proportions
For two successive discounts a and b, final price = original price × (1 − a ÷ 100) × (1 − b ÷ 100). The combined discount percentage is 100 × [1 − (1 − a ÷ 100) × (1 − b ÷ 100)]. Adding the percentages would incorrectly apply both discounts to the original amount.
Check the store's conditions
This example models two percentage discounts applied to the same eligible item in sequence. Fixed-value coupons, maximum savings, exclusions, tax and shipping need separate treatment. Use the discount calculator once for each stage if checking a sequential promotion.
Put the formula into practice
Original price: 100. First discount: 20%. Second discount: 10%.
Final price is 72, representing a combined 28% discount.