Percentages & Ratios

Percentages and ratios are two ways of expressing how quantities relate. The Percentage Calculator covers the four questions that come up most: what is X% of Y, X is what percent of Y, X is Y% of what, and percentage change between two values. The Ratio Calculator works with colon-separated comparisons - simplifying a ratio to lowest terms (two or three parts), solving a proportion for a missing value, comparing two ratios, and converting a ratio to or from a decimal, a percentage, or a fraction.

Between them they connect the everyday forms of proportional reasoning - a discount, a tip, a mix ratio, a scale - and each shows the arithmetic behind the answer. Both run entirely in your browser.