Discount Calculator

What does this tool do?

Three questions, one page: the final price after a discount, the discount behind two prices, and what is left after two discounts applied one after the other.

Two discounts are not added up

A 20 % discount followed by another 20 % is not 40 %. The second one is calculated on what was left after the first:

100 → 20 % off → 80 → 20 % off → 64

That is 36 % off in total, and the difference from 40 % is exactly the mistake this page exists to catch. The result shows the effective discount, so you can compare an offer against a simpler one.

When it is not a discount

If the final price is higher than the original, the tool refuses to answer: that is a surcharge, and calling it a discount would hide it. Percentages outside 0–100 and negative prices are rejected too, each with a sentence saying what is wrong.

Keep in mind

Money is not rounded to cents inside the engine — the result carries the exact figure and the page shows two decimals, so a chain of calculations does not accumulate rounding errors. Everything runs in your browser.