%
Calculation15% × 200

The formula

part=percent100×whole\text{part} = \dfrac{\text{percent}}{100} \times \text{whole}

How it works

A percentage is a part per hundred. The three modes cover the everyday questions: a slice of a total, how big one number is relative to another, and how much something rose or fell.

FAQ

How do I find a percentage of a number?

Divide the percent by 100 and multiply — 15% of 200 is 0.15 × 200 = 30.

What is percentage change?

The difference divided by the original value, times 100. Increases are positive, decreases negative.

Related calculators
Fraction to percentDiscount calculatorTax / VAT calculator

The three percentage questions

Almost every everyday percentage problem is one of three: finding a percentage of a number, working out what percentage one number is of another, or measuring the percentage change between two values. This calculator handles all three from a single screen.

The maths behind it

A percentage is simply a part per hundred. To take a percentage of a number, divide the percentage by 100 and multiply. To find what percentage one value is of another, divide the first by the second and multiply by 100. Percentage change divides the difference between the two numbers by the original value: part=percent100×whole\text{part} = \frac{\text{percent}}{100}\times\text{whole}.