The three percentage formulas
X% of Y = (X ÷ 100) × Y
X is what % of Y = (X ÷ Y) × 100
% change = ((New − Old) ÷ |Old|) × 100
Everyday uses
- Calculating discounts and sale prices.
- Working out tips, taxes and commissions.
- Comparing growth — for example a price or score that went up or down.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 200 is (15 ÷ 100) × 200 = 30.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 out of 150 is (30 ÷ 150) × 100 = 20%.
How is percentage change calculated?
Subtract the old value from the new value, divide by the old value, and multiply by 100. A positive result is an increase; a negative result is a decrease.