Stacked discount calculator

How to use this calculator

Enter the original price and both percentage reductions. The second discount applies to the already-discounted price. Use zero for the second discount if you only have one.

The formula

Final price = original price × (1 − first discount% ÷ 100) × (1 − second discount% ÷ 100). Effective discount% = [1 − (1 − first% ÷ 100) × (1 − second% ÷ 100)] × 100.

A worked example

A $100 item discounted by 20% becomes $80. A further 10% reduces it to $72. The combined saving is $28, an effective 28% discount.

Assumptions & limitations

Successive percentage discounts before taxes and shipping. Does not model fixed-value coupons, minimum-spend conditions, exclusions, or retailer-specific intermediate rounding.

Common questions

Why don’t 20% and 10% make 30%?

The second reduction applies to the smaller remaining price, not the original price.

Does the order matter?

With exact percentage arithmetic, the product is the same in either order. Store rounding rules can produce small differences.

Supporting reference

The method above states this calculator’s assumptions. This reference provides related definitions and technical context.

OpenStax: successive discounts ↗

Formula and worked example checked against automated test cases. About our methodology.