Percentage Calculator
The three percentage questions everyone actually asks — answered instantly as you type.
What is X% of a number?
X is what percent of Y?
X is Y% of what number?
For growth and decline between two values, use the Percent Change Calculator.
About this tool
Percentages are simple until they are in front of you: a 15% tip base, 40% off a price, a score of 43 out of 50 as a percentage. This calculator answers the three everyday forms — “what is X% of Y?” (multiply Y by X/100), “X is what percent of Y?” (divide X by Y, times 100), and the reverse, “X is Y% of what number?” (divide X by Y/100) — live, as you type, with no submit button.
It deliberately does not hide the formula: once you see that a percentage is just a fraction of 100, the calculator becomes a checker rather than a crutch. For comparing a value before and after — prices, weights, scores over time — use the percent change calculator, which uses the “change divided by the original” formula instead.
How to use it
- For “X% of Y”: enter the percent and the number in the first row.
- For “X is what % of Y”: enter both numbers in the second row.
- For “X is Y% of what”: enter the part and the percent in the third row.
- Results update as you type — there is nothing to submit.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number: 15% of 200 = 0.15 × 200 = 30. The first row of this calculator does exactly that.
How do I express a score as a percentage?
Divide what you got by the total and multiply by 100: 43/50 = 0.86 = 86%. That is the second row of this calculator.
What is the difference between percent change and percentage points?
Percent change is relative to the starting value (4% → 5% is a 25% increase), while percentage points measure the raw difference (4% → 5% is +1 percentage point). The percent change calculator handles the first; this page handles plain percentages.