Double Discount Calculator
Find the real combined discount when two percentage-offs are stacked.
How stacked discounts work
When two discounts are applied one after the other, they are not additive. The second discount applies to the already-reduced price, not the original. The formula is:
Final Price = Original × (1 − D1/100) × (1 − D2/100)
Example: $100 with 20% off then 10% off:
$100 × 0.80 × 0.90 = $72. The effective discount is 28%, not 30%.
Why the effective discount is always less than the sum
The second percentage is calculated on a smaller base, so it contributes less than it appears. The bigger the first discount, the larger the gap. Two 50% discounts in sequence produce a 75% effective discount — not 100%.
Frequently asked questions
When do stacked discounts happen?
Common examples: a store-wide 20% off sale combined with a member extra 10% off; a coupon applied on top of a promotional price; or buy-one-get-one deals structured as two sequential reductions. In all cases the discounts multiply, not add.
Is 20% + 10% the same as 30% off?
No. 20% then 10% gives an effective discount of 28%, not 30%. You'd need a single 30% coupon to reach 30% off. The gap grows with larger discounts — 40% + 40% is only 64% off, not 80%.
What's the maximum effective discount from two stacked discounts?
Mathematically, two 100% discounts would give 100% off, but that's not realistic. In practice, the closer each discount is to 100%, the closer the combined effective rate gets — but it always stays below the simple sum.
How does this calculator work?
Enter the original price and two discount percentages. The calculator applies them sequentially — first discount to the original price, second discount to the result — and shows the final price, total savings, and the true effective discount percentage. Everything runs in your browser. Use Share to copy a link with your inputs pre-filled.