Percentage Calculator

Percent means 'per hundred', so a percentage is a fraction with a denominator of 100. This calculator handles the three most common percentage tasks: finding a percentage of a value, finding what percent one value is of another, and calculating change between two values.

Enter values

Results

15% of 200: 30
15 is what % of 200: 7.5%
Change from 15 to 200: +1,233.33%

How is the Percentage calculated?

Enter the two numbers. The calculator answers all three common percentage questions at once — X% of Y, X as a percentage of Y, and the percentage change from X to Y — each rounded to two decimal places. The base always matters: 20% of 150 and 150% of 20 both give 30, so the value after 'of' decides the answer.

Formula

Percentage of a value:  X% of Y = (X ÷ 100) × Y

What percent:  (X ÷ Y) × 100

Percentage increase:  ((new − old) ÷ old) × 100

Percentage decrease:  ((old − new) ÷ old) × 100

Example

What is 15% of 200?
(15 ÷ 100) × 200 = 30

Increase from 80 to 100:
((100 − 80) ÷ 80) × 100 = 25%

Decrease from 100 to 80:
((100 − 80) ÷ 100) × 100 = 20% — the same move is 25% upward but 20% downward, because percentage change is always measured against the value you started from.

Things to remember

Percentage change is always relative to the original value, so the same absolute change gives a different percentage depending on the starting number. Quote the base whenever you compare two growth rates.

Frequently Asked Questions

How do you calculate a percentage?

Divide the part by the whole and multiply by 100. For example, 45 marks out of 60 is (45 ÷ 60) × 100 = 75%. To find a percentage of a number, divide the percentage by 100 and multiply.

How do you calculate percentage increase?

Subtract the original value from the new value, divide by the original value, then multiply by 100. Going from 80 to 100 gives ((100 − 80) ÷ 80) × 100 = 25% increase.

How do you work out 15% of 200?

The answer is 30. Divide 15 by 100 to get 0.15, then multiply by 200: 0.15 × 200 = 30. The reverse check divides 30 by 200 and multiplies by 100, which returns the original 15%.