About the Percentage Calculator
A percentage is just a way of expressing a number as a fraction of 100 — useful shorthand for comparing amounts that would otherwise be hard to compare directly. This calculator covers the three questions people most commonly need a percentage for, in one tool instead of three.
% of a numberanswers questions like "what is 20% of 50?" — handy for discounts, tips, sales tax, and commissions. Is what % flips that around: given two amounts, it tells you what percentage one is of the other — useful for test scores, budget shares, or completion rates. % change measures how much a value grew or shrank between two points — the calculation behind price changes, population growth, and year-over-year statistics.
Every mode uses the standard, unambiguous percentage formula for that calculation — there's no rounding trick or approximation involved. The one thing to watch for: percentage change is a relative measure, so a change from a very small starting number can produce a very large percentage even if the actual difference is small.
Uses the three standard percentage formulas: (percent ÷ 100) × number for 'percent of', (part ÷ whole) × 100 for 'is what percent', and ((new − old) ÷ old) × 100 for percentage change.