Percentage Calculator
What is X% of Y, X is what percent of Y, and percent change from A to B — three modes in one tool.
Reviewed by the WorldCalcs team · Methodology · Last reviewed: June 2026
Result
30
20% of 150 = 30
What is a percentage?
A percentage is a way of expressing a number as a part of 100. "Per cent" literally means "per hundred", so 25% is 25 out of 100, or the fraction 25/100 = 0.25. Percentages make it easy to compare proportions, work out discounts and tips, and describe change. This calculator handles the three most common percentage questions in one place.
How it's calculated
There are three core calculations. To find a percentage of a number, multiply: 20% of 150 = 0.20 x 150 = 30. To find what percentage one number is of another, divide and multiply by 100: 50 out of 200 = 50 divided by 200 x 100 = 25%. To find the percentage change from one value to another, take the difference over the original: from 100 to 150 is (150 - 100) divided by 100 x 100 = +50%.
Example
If a 150-unit item is 20% off, the discount is 0.20 x 150 = 30, leaving 120. If you scored 50 out of 200 on a test, that is 50 divided by 200 x 100 = 25%. And a price rising from 100 to 150 is a 50% increase.
All calculations happen in your browser. Nothing is sent, stored, or tracked.
Results are estimates and may contain errors — for general information only, not professional advice. Always verify before relying on them. Disclaimer
How to use
Pick a mode at the top of the card. Then fill in the two numbers — the result updates instantly as you type.
Percent of: (X ÷ 100) × Y. Is what percent: (X ÷ Y) × 100. Percent change: ((B − A) ÷ A) × 100. A negative result means a decrease.