Discount calculator — sale price and stacked discounts
Work out a sale price, the discount percentage, or the original price before a discount — and see why stacking two discounts does not add them together.
Runs entirely in your browser — nothing is uploaded.
Sets formatting only.
Stacked discounts multiply rather than add: 20% then 10% off is 28% off, not 30%. That is the single most common retail-maths error, in both directions.
How to use
- Choose what you want to find. Sale price, discount percentage, original price, or the effect of stacked discounts.
- Fill in what you know. The result appears immediately.
- For stacked discounts, list them in order. Comma separated, for example 20, 10.
Questions
What is 20% off then another 10% off?
28% off, not 30%. The second discount applies to the already-reduced price: 100 → 80 → 72. Retailers rely on this reading as a bigger saving than it is.
How do I find the original price from a sale price?
Divide by (1 − discount). An item reduced 25% to €75 was €75 ÷ 0.75 = €100. Adding 25% back to €75 gives €93.75, which is wrong.
How do I work out the discount percentage?
Subtract the sale price from the original, divide by the original, multiply by 100. From €80 to €60 is (80 − 60) ÷ 80 = 25% off.
Does the order of stacked discounts matter?
No — multiplication is commutative, so 20% then 10% gives the same final price as 10% then 20%. It matters for coupon terms, not for the arithmetic.