Discount calculator
How much do you really save? Get the final price from a percent-off discount, or find the true discount by comparing two prices.
From percent off to sale price
From two prices to the real discount
The thing to check before the percentage
It isn't how big the discount is: it's which price it starts from. A starting price inflated a few days before the sales makes any percentage look large, which is why Europe has a precise rule: when a shop announces a reduction, the crossed-out price must be the lowest one applied in the previous thirty days. It's the European price directive (transposed in Italy in 2023 into the consumer code) and it applies both in shops and online.
The practical way to check is to compare it with what you remember seeing, or with another shop: if you've never seen anyone charged the full price, that percentage is measuring an invented number.
How to tell whether a deal is genuine
The most reliable check is the price history: if today's price really is the lowest it has been in recent months, the deal is real. Price-tracking sites and browser extensions chart how an item's price has moved over time and flag verified all-time lows, so a ten-second look at the graph tells you whether that "50% off" banner deserves your money or your skepticism.
The sum, and how to do it in your head
Final price = price × (1 − discount ÷ 100). The quick way, in front of the shelf, is to think in terms of what's left rather than what's taken off: −30% means paying 70%, so you multiply by 0.7. On 89: 10% is 8.90, 30% is three times that (26.70), and the final price is 62.30.
The other way round, from the two prices: discount percentage = (full price − discounted price) ÷ full price × 100. The division goes on the full price, and that's the commonest mistake: dividing by the discounted price gives a bigger, wrong number. From 100 to 80 the discount is 20% (twenty divided by a hundred), not 25.
Two discounts in a row don't add up
A −20% followed by a −10% isn't −30%, it's −28%, because the second applies to an already reduced price. With factors it's immediate: 0.80 × 0.90 = 0.72, that is 72% of the starting price. It also holds for a voucher applied on top of the sale price, and it holds in reverse order with the same result: the total discount doesn't change if you swap the two.
The same arithmetic explains something else useful: after a 20% discount, getting back to the old price needs a rise of 25%. It's why the price you see after the sales looks like it went up more than it had come down.
Nearby tools
If you have the two prices and want the percentage, the second part of this page does it; to apply any increase or reduction Increase or reduce by a %. To compare two packs of different weight there is Price per kg, and for the price with or without tax VAT calculator.