% Percentage Calculator
Three ways to calculate percentages: find a percent of a number, find what percent one number is of another, or find percentage change.
What is X% of Y?
Result
Percentage Formulas
A percentage expresses a number as a fraction of 100. This free percentage calculator covers the four most common percentage problems: finding a percent of a number, finding what percent one number is of another, and calculating percentage increase or percentage decrease (percent change) between two values.
X% of Y
Worked example: What is 20% of 150? (20 ÷ 100) × 150 = 30.
X is what percent of Y
Worked example: 30 is what percent of 150? (30 ÷ 150) × 100 = 20%.
Percentage Increase / Percentage Decrease (Percent Change)
A positive result is a percentage increase; a negative result is a percentage decrease. Worked example: A price rises from 80 to 100. ((100 − 80) ÷ 80) × 100 = +25% increase. If it instead fell from 100 to 80: ((80 − 100) ÷ 100) × 100 = −20% decrease.
How to Use This Percentage Calculator
- Choose a mode above: "X% of Y", "X is what % of Y", or "% Change (X to Y)".
- Enter your two numbers into the input fields.
- Your result updates instantly — no need to press calculate unless you prefer to.
- For percentage increase/decrease, enter the original value as "From" and the new value as "To".
Frequently Asked Questions
How do I calculate a percentage increase?
Subtract the original value from the new value, divide by the original value, then multiply by 100. A positive result means an increase. For example, going from 80 to 100 is a 25% increase.
How do I calculate a percentage decrease?
Subtract the new value from the original value, divide by the original value, then multiply by 100. For example, going from 100 to 80 is a 20% decrease.
What's the difference between percentage change and percentage points?
Percentage change is a relative change (e.g., going from 20% to 25% is a 25% increase). Percentage points measure the absolute difference between two percentages (e.g., 20% to 25% is a 5 percentage point increase).
How do I find what percent one number is of another?
Divide the first number by the second, then multiply by 100. For example, 30 is 20% of 150 because (30 ÷ 150) × 100 = 20.
What if the "from" value in percentage change is zero?
Percentage change is undefined when the starting value is zero, since you cannot divide by zero. The calculator will show a validation note in that case.