Two everyday percentage sums in one place: find what a percentage of a number is, or work out one number as a percentage of another. No sign-up, nothing to download – just type and calculate.
Percentage Calculator
What is X% of Y?
X is what percent of Y?
Want the method behind it? Read our guide: How to Calculate a Percentage of a Number
How to use the Percentage Calculator
- Decide which of the two questions you are asking: “What is X% of Y?” or “X is what percent of Y?” Each has its own box on the tool.
- For the first question, type the percentage in the “Percent (X)” box and the full amount in the “Of number (Y)” box, then press “Calculate”.
- For the second question, type the smaller part in the “Part (X)” box and the total it belongs to in the “Whole (Y)” box, then press “Calculate”.
- Read the answer sentence that appears under the box you used.
The formula
For the first question, the working is: result = X ÷ 100 × Y. In plain words, you turn the percentage into a decimal by dividing by 100, then multiply by the full amount. So 15% of any number is that number multiplied by 0.15.
For the second question, the working is: percentage = X ÷ Y × 100. You divide the part by the whole to get a decimal, then multiply by 100 to state it as a percentage. The part and the whole are the two inputs that matter most here — the whole is the total the part was taken from, such as the full marks on a test or the original price of an item.
Worked example
First question: what is 15% of 240? Enter 15 in the Percent box and 240 in the Of number box. The answer is 36, because 15 ÷ 100 = 0.15, and 0.15 × 240 = 36. This is the sum you would use for a 15% discount or a 15% tip on a bill of 240.
Second question: 45 is what percent of 180? Enter 45 as the Part and 180 as the Whole. The answer is 25%, because 45 ÷ 180 = 0.25, and 0.25 × 100 = 25. So 45 is exactly one quarter of 180.
Common mistakes
- Swapping the part and the whole in the second box. The part goes first; the total it came from goes second.
- Typing the decimal instead of the percentage. Enter 15 for 15%, not 0.15 — the tool divides by 100 for you.
- Using the wrong whole. If a price dropped from 200 to 150, the “whole” for the drop is the original 200, not 150.
- Expecting a percentage change answer from these two boxes. They give a share of a total, which is a different question from how much something has risen or fallen.
Frequently asked questions
Q: Can a percentage be more than 100%?
Yes. It simply means the part is bigger than the whole you are comparing it with. If a shop sells 250 tickets against a target of 200, it has reached 125% of its target.
Q: How do I find the price after a percentage discount?
Work out the discount amount with the first box, then take it away from the original price. A 15% discount on 240 is 36, so the price you pay is 240 − 36 = 204.
Q: What is the difference between percent and percentage points?
Percent is a share of a total. Percentage points describe the gap between two percentages — if a rate rises from 10% to 12%, that is a rise of 2 percentage points, even though it is a 20% rise relative to the original rate.