Percentage Calculator

Percentage calculations appear in nearly every domain: finance (interest rates, return on investment, inflation), retail (discount pricing, sales tax, margin), health (body fat percentage, nutrient daily values), academics (grade calculation, test scores), and statistics (survey results, growth rates). Despite this ubiquity, percentage calculations are a surprisingly common source of errors — particularly the distinction between percentage of a value ("what is 15% of 200") and percentage that one value is of another ("25 is what % of 200"). This tool makes both calculations explicit so you always get the right answer for the right question.

The tool covers three fundamental percentage operations: finding a percentage of a number (e.g., calculating a 20% tip on a restaurant bill), finding what percentage one number is of another (e.g., a student scored 47 out of 60 — what percent is that?), and calculating percentage change between two values (e.g., a product was €80, now €68 — what's the percentage decrease?). All calculations use full floating-point arithmetic for accuracy. Results display to two decimal places by default, which is appropriate for financial and academic contexts.