Sale Price Calculator
Calculate a sale price from an original price and discount percentage, or reverse it to find the original price from a known sale price and discount.
$
%
Original Price
$100.00
Original Price
$100.00
Sale Price
$80.00
Amount Saved
$20.00
How the Sale Price Calculator Works
This calculator works in both directions. Going forward, it takes an original price and a discount percentage to find the sale price. Going in reverse — the more unusual calculation — it starts from a sale price you already know (say, a receipt or a tag) and the discount percentage applied, and works backward to find the original, pre-discount price.
Original Price = Sale Price / (1 − Discount %)
Example
If an item sells for $80 after a 20% discount, dividing $80 by (1 − 0.20) gives an original price of $100 — meaning $20 was saved. Going the other way, a $100 item with a 20% discount sells for $80, the same relationship in reverse.
Common Use Cases
- Working out the original price of an item from a discounted receipt or price tag.
- Checking whether an advertised discount percentage matches the actual price drop.
- Calculating a sale price directly from an original price and discount.
- Verifying markdown math when auditing retail pricing.
FAQs
Why isn't the original price just the sale price plus the discount percentage added back?
Because the discount percentage was applied to the original price, not the sale price. Adding 20% to an $80 sale price gives $96, not the correct $100 original price — you have to divide by (1 − discount %) to reverse the math correctly.
How do I stack multiple discounts?
Apply them sequentially, not by adding percentages — a 10% discount followed by another 10% off is a 19% total discount, not 20%, since the second discount applies to the already-reduced price.
What happens if the discount is 100%?
A 100% discount means the sale price is $0, and reversing from a $0 sale price can't determine a unique original price — the calculator can't solve for the original price when the discount is exactly 100%.