How to Calculate Discount Percentage
Discount math seems simple until you need to reverse it — figuring out what percentage off a sale price actually represents.
Forward: finalPrice = originalPrice × (1 − discount%). Reverse: discount% = (originalPrice − finalPrice) ÷ originalPrice × 100.
Stacked discounts don't simply add
Two 20% discounts applied in sequence do not equal a 40% discount — the second 20% applies to the already-discounted price. $100 at 20% off twice: $100 → $80 → $64, an effective 36% discount, not 40%.
Reverse mode: figuring out what discount was applied
Given an original price of $200 and a sale price of $150: discount% = (200−150) ÷ 200 × 100 = 25% — useful for verifying a marked-down price actually matches its advertised discount.
Try Free Web Tools Mentioned in This Guide
Frequently Asked Questions
How do I calculate two stacked discounts correctly?↓
Apply the first discount, then use the resulting price as the 'original price' for the second calculation — never add the percentages together.
Can a discount percentage exceed 100%?↓
No — a 100% discount means the item is free; anything beyond that isn't a valid discount calculation.