How to Calculate a Discount (Percent Off, Stacked Deals, Real Savings)

The one formula you need

Discount amount = original price × percent off ÷ 100. What you pay = original price − discount amount.

Example: a jacket at 80 with 25% off. Discount = 80 × 25 ÷ 100 = 20. You pay 80 − 20 = 60, and you save 20.

The faster route is to multiply by what's left: 25% off means you pay 75% of the price, so 80 × 0.75 = 60. Same answer, one multiplication.

Percentages don't stack the way ads imply

"20% off, plus an extra 10% at checkout" is not 30% off. The second discount applies to the already-reduced price, not the original.

On an 80 item: 20% off leaves 64. Then 10% off 64 is 6.40, so you pay 57.60 — a total saving of 22.40, which is 28% off, not 30%. Every stacked percentage is smaller than it looks because it is taken from a smaller number.

Run each step in order and you'll never over-estimate a sale.

Bundles and "buy 2 get 1 free"

Bundle offers hide their real discount. Three items for the price of two means you pay for 2 and receive 3, so the effective discount is 1 ÷ 3 = 33.3% — but only if you actually wanted all three.

The general rule: effective discount = (value received − what you pay) ÷ value received. If you'd only have bought two anyway, the third item is not a saving at all.

Comparing "save 15" with "20% off"

The bigger-looking number isn't always the better deal. On an 80 purchase, 20% off is worth 16, so it beats a flat 15 saving. On a 60 purchase, 20% off is worth 12, and the flat 15 wins.

The break-even point is where the two are equal: 15 ÷ 0.20 = 75. Above 75 the percentage is better; below it, the flat amount is. That's why stores set minimum spends on percentage deals.

Do it in seconds

Type the original price and the percent off into the Discount Calculator and it shows what you pay and what you save, with quick buttons for the common 10, 15, 20, 25, 30 and 50% offers.

For a stacked deal, run the first discount, then use its "you pay" figure as the starting price for the second. Two entries, and you'll know exactly what the deal is worth.