Orpheus

Discount Calculator

What you pay, what you save, and what stacked offers really mean.

Inputs
30%
0%

For stacked offers such as “extra 20% off sale prices”.

You pay
84.00
You save
36.00
Effective discount
30%
final = price × (1 − d₁) × (1 − d₂)

Every tool runs entirely in your browser. Your files are never uploaded to a server.

Multiply the price by one minus the discount. Two stacked discounts multiply rather than add: 30 percent off followed by a further 20 percent is 44 percent off in total, not 50.

How to use Discount Calculator

  1. Enter the original price. The pre-discount figure on the label.
  2. Set the discount. The advertised percentage off.
  3. Add a second offer if there is one. For “extra 20% off sale items” at the checkout.

About calculating a discount

The arithmetic of discounts is simple and the presentation of them is not, which is where most of the confusion is manufactured rather than accidental. Stacking is the clearest example. A sign reading "30% off, plus an extra 20% at the checkout" invites the reader to add the numbers, and the true figure is always lower — 44 percent here — because the second reduction applies to a smaller base. The gap grows with the size of the discounts: 50 and 50 is 75 percent off, not 100, which is why nothing is ever free. The second area worth understanding is the reference price. A percentage is meaningless without knowing what it is a percentage of, and consumer protection rules in the UK, EU and elsewhere require that a "was" price reflect a price genuinely charged for a meaningful period — usually thirty days — precisely because inflating it before a sale is an easy way to manufacture a discount that never existed. Mixed offers behave differently again: if one discount is a fixed amount and the other a percentage, the order does change the outcome, and applying the fixed amount last always leaves you paying less.

Frequently asked questions

Why is 30% off plus 20% off not 50% off?
Because the second discount applies to the already-reduced price, not the original. 30 percent off 100 is 70; 20 percent off 70 is 56. That is 44 percent off in total. Discounts stack multiplicatively, and the gap widens as the percentages grow.
How do I work out the percentage off from two prices?
Subtract the sale price from the original, divide by the original, multiply by 100. From 120 to 84 is a saving of 36, which is 30 percent. Dividing by the sale price instead is a common error and overstates the discount.
Does the order of two discounts matter?
For percentages, no — multiplication commutes, so 30 then 20 gives the same result as 20 then 30. It does matter when one of them is a fixed amount off rather than a percentage, in which case taking the fixed amount last is better for you.
What is a reference price and why does it matter?
The "was" price a discount is measured against. Consumer law in many countries requires it to be a price the item was genuinely sold at recently, precisely because an inflated reference price makes an ordinary price look like a bargain.

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