How to Calculate Percentages
Understand the most common percentage formulas with practical examples.
Finding a percentage of a number
Convert the percentage to a decimal and multiply: 15% of 80 = 0.15 × 80 = 12.
Finding what percentage one value is of another
Divide the part by the whole and multiply by 100: 12 / 80 × 100 = 15%.
Percentage change
Use (new − original) / original × 100. If the result is positive, the value increased; if negative, it decreased.
Discounts
For a 20% discount on a 150 price, calculate 20% of 150 (30), then subtract it from 150 to get 120.