PRACTICAL GUIDE
Percentage Calculations Explained With Simple Examples
Understand percentage-of, percentage-change and reverse percentage calculations with straightforward formulas and examples.
Find a percentage of a number
To find X percent of Y, convert X to a decimal and multiply by Y. For example, 20% of 150 is 0.20 × 150 = 30.
Find what percentage one number is of another
Divide the part by the total and multiply by 100. If 30 out of 150 units match a condition, 30 ÷ 150 × 100 = 20%.
Calculate percentage change
Subtract the old value from the new value, divide the difference by the old value, then multiply by 100. A negative result represents a decrease.
Be careful with percentage points
A change from 20% to 25% is an increase of five percentage points, but the relative percentage increase is 25%. The two measurements answer different questions.