How to Calculate Percentages
1. Finding X% of Y
Result = Y × (X / 100)
Example: What is 15% of 300? → 300 × 0.15 = 45
2. Finding What Percentage X is of Y
Percentage = (X / Y) × 100
Example: 45 is what % of 300? → (45 / 300) × 100 = 15%
3. Percentage Change
Change = ((New - Old) / |Old|) × 100
Example: From 200 to 250 → ((250 - 200) / 200) × 100 = 25% increase
4. Percentage Difference
Difference = (|X - Y| / ((X + Y) / 2)) × 100
Example: Between 80 and 100 → (20 / 90) × 100 = 22.22%
5. Increase or Decrease by a Percentage
Increase: X × (1 + Y/100)
Decrease: X × (1 - Y/100)
Example: Increase 80 by 25% → 80 × 1.25 = 100
Decrease 200 by 10% → 200 × 0.90 = 180
Frequently Asked Questions
How do I calculate what X% of Y is?
To find X% of Y, multiply Y by X and divide by 100. Formula: Result = Y × (X / 100). For example, 25% of 200 = 200 × 0.25 = 50.
How do I calculate percentage change?
Percentage change = ((New Value - Old Value) / |Old Value|) × 100. If the result is positive it's an increase; if negative, it's a decrease.
What is the difference between percentage change and percentage difference?
Percentage change measures change from an original value to a new value (directional). Percentage difference measures the difference between two values relative to their average (non-directional), and is always expressed as a positive number.
How do I find what percentage X is of Y?
Divide X by Y and multiply by 100. Formula: Percentage = (X / Y) × 100. For example, 30 is what % of 150? (30 / 150) × 100 = 20%.
How do I increase a number by a percentage?
Multiply the number by (1 + percentage/100). For example, increase 80 by 25%: 80 × 1.25 = 100.
How do I decrease a number by a percentage?
Multiply the number by (1 - percentage/100). For example, decrease 200 by 15%: 200 × 0.85 = 170.
How do I convert a fraction to a percentage?
Divide the numerator by the denominator and multiply by 100. For example, 3/8 = 0.375 × 100 = 37.5%.