% Percentage Calculator

How to Calculate Percentages

Percentages are one of the most commonly used mathematical concepts in daily life — from sales discounts to tax rates, exam scores to financial calculations. The word "percent" means "per hundred," so a percentage is always a fraction of 100.

Three Common Percentage Problems

• What is X% of Y? Multiply Y by X/100. Example: 25% of 200 = 200 × 0.25 = 50.
• X is what % of Y? Divide X by Y and multiply by 100. Example: 50 is what % of 200? = (50/200) × 100 = 25%.
• Percentage Change: ((New - Old) / |Old|) × 100. Positive = increase, negative = decrease.

Percentages are essential in finance (interest rates, returns), shopping (discounts, tax), academics (grades, scores), and data analysis (proportions, growth rates).