Stacked Discount Calculator
Apply up to three discounts one after another and see why “20% + 10% + 5%” is never a 35% discount.
How it works
Final = price × (1 − d₁) × (1 − d₂) × (1 − d₃) · Effective discount = (1 − final ÷ price) × 100
Stacked discounts multiply, they do not add. Each discount applies to whatever price is left after the previous one, so the second cut is taken from a smaller number. Adding 20% + 10% + 5% suggests 35% off, but the real saving is only about 31.6% — the more discounts you stack, the wider that gap grows.
Worked example
On $100: 20% off leaves $80, then 10% off leaves $72, then 5% off leaves $68.40. You saved $31.60, a true 31.6% discount — well short of the 35% you would get by adding the rates.
Frequently asked questions
Why don’t stacked discounts just add up?
Each successive discount is applied to the already-reduced price, not the original. Because the base shrinks with every step, the combined effect is always less than the sum of the individual rates.
Does the order of the discounts matter?
No — multiplication is commutative, so applying 20% then 10% gives the exact same final price as 10% then 20%. The order only matters for tax, which this tool does not add.
What single discount equals the stack?
The “true effective discount” figure. For 20%, 10% and 5% stacked, that single equivalent is 31.6% off.
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This calculator is for educational purposes. Double-check important results before acting on them.