Discount Calculator

What this calculator does

Shop discounts are advertised as percentages, but what you actually need is two numbers in currency: what the item now costs, and how much you are keeping in your pocket. This calculator gives you both, and the second tab does the reverse — feed it a before-and-after price and it tells you the real discount percentage, which is handy when a tag shows two prices but no percentage at all.

How to use it

On the first tab, enter the marked price and the advertised discount.
Read off the price you pay, the amount saved, and the working.
On the second tab, enter the original and sale prices to reveal the actual percentage off.

The formulas

Amount savedSaving = Price × (Discount ÷ 100)

Price you paySale price = Price × (1 − Discount ÷ 100)

Finding the discount percentageDiscount % = ((Price − Sale price) ÷ Price) × 100

Worked example

A 1,299 pair of headphones at 25% off

Saving: 1,299 × 0.25 = 324.75
Price to pay: 1,299 − 324.75 = 974.25
Or in one step: 1,299 × 0.75 = 974.25

Stacked discounts: the 50 + 20 trap

"50% off, then an extra 20% at the till" sounds like 70% off. It is not. The second discount applies to the already-reduced price, so you pay 0.5 × 0.8 = 0.4 of the original — a 60% discount. The gap between the advertised impression and the real figure is ten full percentage points.

To work out any stack, multiply the remaining fractions together. Three discounts of 30%, 10% and 5% give 0.7 × 0.9 × 0.95 = 0.5985, so you pay 59.85% of the original and save just over 40%.

Discounts before or after tax Whether a discount is applied before or after tax changes the final figure, and different retailers and jurisdictions do it differently. Check the receipt rather than assuming, and use the tax calculator to check the tax portion separately.

Common mistakes

Adding stacked discounts together. As above — multiply the remainders, never add the discounts.

Trusting an inflated "was" price. The percentage is only as honest as the original price it is calculated from. A large discount off a price nobody ever paid is not a saving.

Confusing a discount with a markup. Buying at 40% off a 100 price gives 60. Selling that at a 40% markup gives 84, not 100. Discounts and markups are taken from different bases, which is covered on the markup calculator.

Frequently asked questions

How do I calculate 25% off a price?

Multiply the price by 0.75. In general, subtract the discount from 100, divide by 100, and multiply by the price — so 35% off means multiplying by 0.65.

How do I work out the discount percentage from two prices?

Subtract the sale price from the original, divide by the original price, and multiply by 100. The second tab of the calculator does this for you.

Is 50% off then 20% off the same as 70% off?

No. The second discount comes off the already-reduced price, so you pay 40% of the original — a 60% discount overall, not 70%.

Can I enter a discount over 100%?

No, and the calculator will tell you why. A discount above 100% would mean the shop paying you to take the item, so the input is rejected as an error rather than producing a nonsense price.

Does the calculator handle currency?

It works with plain numbers, so it fits any currency. Enter the amount without a currency symbol and read the answer in the same currency you typed in.

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