Ratio Calculator
Enter your values below and click Calculate for instant results.
Simplify ratios, find missing values in proportions, and scale ratios by any factor.
Enter your values below and click Calculate for instant results.
A ratio expresses the relative sizes of two or more quantities. A ratio of 3:4 means for every 3 of one thing, there are 4 of another. Ratios appear in cooking (recipe proportions), maps (scale), finance (debt-to-equity ratios), and everyday comparisons of any kind.
A ratio and a fraction express the same relationship differently. The ratio 3:4 is equivalent to the fraction 3/4. To simplify a ratio, divide both values by their greatest common divisor, exactly as you would simplify a fraction.
A proportion states that two ratios are equal: a/b = c/d. This allows you to solve for a missing value when three of the four are known. Cross-multiplication is the standard technique: if 3/4 = 9/d, then 3d = 36, so d = 12. This calculator handles that algebra automatically in the "find equivalent ratio" mode.
Ratios are fundamental in cooking and baking (scaling a recipe up or down), mixing solutions (diluting chemicals or paints to a target concentration), map reading (converting map distances to actual distances), financial analysis (comparing income to debt), and photography (aspect ratios for image dimensions).