Discount Calculator
Find the sale price and how much a discount actually saves — or turn it around: work out the discount percent from two prices, or the original price from a sale. Everything is computed in this browser tab.
Discount
Result
Private by design. This page has no backend. The maths is done by JavaScript on your own device — the numbers never leave this page.
The three calculations
All three pick a question and answer it as you type. Answers are rounded to two decimal places for display, but the underlying values keep their full precision so nothing drifts between keystrokes. A discount percent over 100 — which would make the store pay you — is treated as an error.
Sale price
The everyday one: what is 30% off of 80? The sale price is
80 × (1 − 30/100) = 56, and the savings are the 24 that fell off. This
is the number to trust when a shop says “extra 15% at the till” and you want the
real total.
Discount percent
Backwards from two prices: a jacket marked down from 120 to 84 has lost
36, which is 36/120 = 30%. If the “sale price” is higher
than the original, the result reads as an increase — honest, if not what you hoped.
Original price
“I paid 84 and it was 30% off — what did it cost before?” The original is
84 / (1 − 30/100) = 120. A 100% or larger discount has no original to
recover, so that combination is rejected rather than divided by zero.
The compound-discount trap
Two “20% off” promotions in a row are not 40% off. Each applies to the price before it: 100 becomes 80 and then 64 — a real discount of 36%. Run the first result through the tool again if a shop stacks deals, and you will see the true saving.
Common uses
Checking a sale really saves more than the label implies, converting a discount into the fraction it actually is, reconstructing list prices from receipts, and comparing “20% off” against “buy one get one half price” when the offers are hard to eyeball.
How to use the Discount Calculator
- Enter the original price and the discount percentage to see the sale price and savings.
- Or switch modes to work from a sale price back to the discount percent or the original price.
- Read the result as you type.
Frequently asked questions
Can it find the discount percentage from two prices?
Yes. Enter the original and the sale price and it calculates the percentage saved.
Does it show how much money I save?
Yes. The savings amount is shown alongside the final sale price.
Can I stack multiple discounts?
Yes. Apply successive discounts to model stacked offers.