How to calculate a discount
Updated on June 30, 2026 · by Rafael Rossi
A discount is a percentage reduction off the price. Calculating it on the spot helps you avoid fake promotions and compare offers quickly.
The formula
final price = price × (1 − discount/100)
The amount saved is price × (discount/100). The trick: turn the discount into a factor — 30% off becomes × 0.70.
Step-by-step example
A $250 item at 30% off:
- Savings: 250 × 0.30 = $75
- Final price: 250 × 0.70 = $175
Stacked discounts do NOT add up
The most common mistake. "20% + 10%" is not 30%. Each applies to the price already reduced by the previous one:
0.80 × 0.90 = 0.72 → 28% off total (not 30%). Order doesn't matter.
Finding the original price
If an item sold for $68 at 15% off, the full price was 68 ÷ 0.85 = $80. Divide by the factor; don't add the percentage back.
FAQ
"Buy 3, pay 2" is what % off? You pay 2 of 3, i.e. 66.7% of the value — a 33.3% discount.
Is a cash discount worth it? Usually yes, if you have the money — it typically beats what the cash would earn invested over the period.