Percentage Off / Sale Price Calculator
Find the sale price and savings from any percentage discount, or work backwards from two prices to the discount.
Supports stacked discounts and sales tax.
Percentage off calculations are used in retail, finance, and everyday budgeting. The core formula converts a discount percentage into an actual price reduction.
Sale price formula:
Sale Price = Original Price × (1 − Discount% / 100)
Discount amount formula:
Discount Amount = Original Price × (Discount% / 100)
Finding the discount percentage from prices:
Discount% = ((Original Price − Sale Price) / Original Price) × 100
Worked example 1, store discount:
Original price: $129.99. Discount: 35%.
Discount Amount = $129.99 × 0.35 = $45.50
Sale Price = $129.99 − $45.50 = $84.49
Worked example 2, reverse calculation:
Original: $200. Sale price: $155.
Discount% = ((200 − 155) / 200) × 100 = (45 / 200) × 100 = 22.5%
Stacked discounts:
When two discounts are applied sequentially, they do NOT simply add together.
Final Price = Original × (1 − D₁/100) × (1 − D₂/100)
Example: 20% off then an additional 10% off a $100 item.
= $100 × 0.80 × 0.90 = $72.00
Combined effective discount: 28%, not 30%.
With tax:
Final Price = Sale Price × (1 + Tax Rate / 100)
Example: $84.49 sale price + 8% tax:
= $84.49 × 1.08 = $91.25
Quick mental math tip: For 25% off: divide the price by 4. For 10% off: move the decimal left one place. For 15% off: take 10% and add half of that.
Two ways to say the same thing
“40% off” and “60% of the price” are the same claim, and shops pick whichever number sounds better. A 40% sign feels generous; the same item advertised as “pay only 60%” would feel stingy for no reason at all. The calculator prints both so you can see them side by side.
The reverse mode is for when you have the two prices and want the percentage. That is the number worth checking, because it is the one the sign is asserting. If the shop claims 50% off and the arithmetic says 31%, either the “original” price is not one they have ever charged or something has been rounded generously.
The anchor price problem
A percentage off is only meaningful relative to a price someone actually paid. Furniture and mattress retailers are the notorious case: a list price that exists purely to be crossed out makes any discount percentage arbitrary. Consumer protection rules in the UK and the EU now require that the reference price be one charged for a reasonable period before the sale, and the US Federal Trade Commission takes a similar line, but enforcement is uneven. Compare against what other shops charge, not against the number with a line through it.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.