% Percentage Calculator
Find percentages three ways: What is X% of Y? What percent is X of Y? Or X is Y% of what?
Understanding Percentages
A percentage is a way of expressing a number as a fraction of 100. The word itself comes from the Latin per centum, meaning "by the hundred." Percentages appear constantly in daily life — sale discounts, tax rates, interest rates, test scores, nutrition labels, and statistical data all use them because they provide an immediate sense of proportion that raw numbers often obscure.
The Three Core Percentage Problems
Almost every percentage question falls into one of three categories. First: What is X% of Y? — used for calculating a tip, a discount, or a tax amount (e.g., 18% of $85). Second: What percent is X of Y? — used to express a score or ratio as a percentage (e.g., 34 correct out of 40 questions = 85%). Third: X is Y% of what? — used when working backwards from a result to find the original value (e.g., $42 is 30% off, so what was the original price?). This calculator handles all three.
Percentage Change vs. Percentage Points
A common source of confusion is the difference between a percentage change and a percentage point change. If an interest rate rises from 3% to 4%, that is a 1 percentage point increase — but it is a 33% increase in the rate itself. Journalists and marketers sometimes conflate these, so knowing the distinction helps you interpret data accurately. Percentage change = (new − old) / old × 100.