How to Calculate Percentages
Percentages express a number as a fraction of 100. Three formulas cover almost every percentage problem.
What is X% of Y?
Multiply Y by X and divide by 100. Example: 15% of 200 = (200 × 15) ÷ 100 = 30. Used for tips, discounts, and tax calculations.
X is what percent of Y?
Divide X by Y and multiply by 100. Example: 45 is what % of 180? (45 ÷ 180) × 100 = 25%. Used for grades and survey results.
How do I calculate percentage change?
Use ((New − Old) ÷ Old) × 100. Example: price goes from $80 to $100 → ((100 − 80) ÷ 80) × 100 = 25% increase.
What is 15% of 200?
15% of 200 = (200 × 15) ÷ 100 = 30. Enter 15 and 200 in the "X% of Y" tab above for instant confirmation.