Percentage Calculator
Answer the three questions people actually ask about percentages — what is X% of Y, what percent is X of Y, and what changed by how much.
How it works
A compact workflow from input to download.
Pick the question
Choose which of the standard percentage problems you are solving.
Enter your numbers
Fill in the two values the question needs.
Read the answer
The result appears instantly, with the working shown so you can check it.
Frequently asked questions
How do I find X% of Y?
How do I express one number as a percentage of another?
What is the difference between percentage points and percent?
Are my numbers sent anywhere?
Percentages are ratios in disguise
The word comes from the Latin per centum, meaning 'by the hundred', and that is all a percentage is — a ratio expressed with the denominator fixed at 100. The reason this is so useful is comparability. A ratio of 37 out of 250 and a ratio of 61 out of 400 are genuinely hard to compare at a glance; convert both to percentages, 14.8% and 15.25%, and the comparison is instant. Fixing the denominator strips away the differing sizes of the things being compared and leaves only the proportion, which is exactly why percentages are the lingua franca of statistics, finance, discounts, test scores and opinion polls.
The trap of percentages of percentages
A percentage always refers to some base, and an enormous amount of confusion comes from losing track of which base. If a price rises 50% and then falls 50%, you do not return to where you started — 100 becomes 150, and 50% of 150 is 75, so you end up 25% below the original price. The rise and fall were percentages of different bases. The same asymmetry means a stock that loses 50% must gain 100% just to break even. It is why a shop offering '50% off, then a further 20% off' is not offering 70% off but 60%. Whenever percentages are chained, ask what each one is a percentage of, because the answer is rarely the same number twice.
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