Stacked discount calculator
50% and then an extra 20% is not 70%. Here you see the real final price and the single discount you are actually being given.
Your figures
Result
- 1.º descuento (50 %)50 €83,3 %
- 2.º descuento (20 %)10 €16,7 %
- Single equivalent discount
- 60.00%
- You save
- $60.00
- What it would look like added up
- 70.00%
- Gap between what it looks like and what it is
- 10.00%
Paso a paso
| Paso | Se aplica sobre | Descuenta | Queda en |
|---|---|---|---|
| 1.º descuento (50 %) | $100.00 | $50.00 | $50.00 |
| 2.º descuento (20 %) | $50.00 | $10.00 | $40.00 |
What we assume
- Each discount applies to the price already reduced by the previous one, which is how shops actually do it.
- Stacked discounts never add up: two of 50% leave 25% of the price, not zero.
- Tax is not included. Enter the price in whichever form you want the answer.
How it is calculated
Each discount multiplies what is left after the previous one:
final = price x (1 - d1) x (1 - d2) x (1 - d3)
That is why they never add up. A 50% discount leaves half; a further 20% takes a fifth off that half, not off the original price.
The single equivalent discount
It is the one discount that would leave the same final price:
equivalent = 1 - (1 - d1) x (1 - d2) x (1 - d3)
50% and 20% look like 70% and are really 60%. The gap grows with the number of discounts, which is exactly why "extra discount on already reduced items" reads so well on a poster.
An example
A price of 100 with 50% and then 20% ends at 40. That is a single discount of 60%, not the 70% it appears to be.
Frequently asked questions
Does the order of the discounts change the result?
No. Multiplication is commutative, so 50% then 20% gives exactly the same as 20% then 50%. What does change the result is whether a discount applies before or after tax.
Can two discounts ever add up to the advertised total?
Only if one of them is zero. Any two real discounts always come to less than their sum.
What about "second item half price"?
That is a different offer: it is a 25% discount on the pair, not 50%. This calculator handles discounts on a single price.
Keep calculating
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Updated on 2026-08-26. Calculations run in your browser; nothing you type is sent to a server.