Percentage Calculator
Solve everyday percentage questions quickly.
What is X% of Y?
X is what percent of Y?
Percentage change from X to Y
Everything is computed in your browser as you type.
Frequently asked questions
How do I calculate what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 out of 120 is 30 divided by 120 times 100, which equals 25 percent. This calculator does that step for you when you use the X is what percent of Y mode.
How do I find X percent of a number?
Multiply the number by the percentage expressed as a decimal. For instance, 15 percent of 200 is 200 times 0.15, which equals 30. Enter the two values and the tool returns the result instantly.
How is percentage change calculated?
Subtract the old value from the new value, divide by the old value, then multiply by 100. A move from 80 to 100 is a 25 percent increase, and a move from 100 to 80 is a 20 percent decrease.
What is the difference between percentage change and percentage points?
Percentage change is relative to the starting value, while percentage points measure the raw arithmetic gap between two percentages. Going from 10 percent to 15 percent is a 5 percentage point rise but a 50 percent relative increase.
Does this calculator send my numbers to a server?
No. Every calculation runs entirely in your browser using JavaScript, so nothing you type is uploaded or stored anywhere.
Can it handle negative numbers and decimals?
Yes. You can enter negative values and decimal fractions, and the percentage formulas apply the same way, including negative percentage changes when a value drops below zero.
Why do I sometimes see a long decimal in the result?
Percentages often do not divide evenly, so the exact answer can have many decimal places. The tool shows a rounded figure for readability, but the underlying math is precise.