Why stacked discounts aren't just added together
A common mistake during sales season: seeing "25% off" and then an extra "10% off" and assuming that's 35% off the original price. It isn't — the second discount applies to the already-reduced price, not the original, so two stacked discounts are always slightly less generous than their sum suggests. This calculator handles that correctly if you enter a second, stacked discount.
The math
| Step | Formula |
|---|---|
| Price after first discount | original × (1 − discount₁ ÷ 100) |
| Price after second discount | previous price × (1 − discount₂ ÷ 100) |
For example: a $100 item with 25% off drops to $75. A further 10% off that $75 (not the original $100) brings it to $67.50 — a combined discount of 32.5%, not 35%. The gap grows with bigger percentages, which is worth knowing before assuming a "50% + 20%" sign means 70% off.