Proportion is the size or amount of one thing compared to another, or how parts relate to a whole. When a recipe calls for ingredients in the right proportions, it means the amounts need to balance correctly: too much flour makes cookies dry, too little makes them flat. When an artist draws a face, getting the proportions right means making the eyes, nose, and mouth the correct sizes relative to each other.

In mathematics, proportion shows up as ratios and fractions. If your class has 12 boys and 18 girls, the proportion of girls is 18 out of 30 total students, or three-fifths. If you're building a scale model of a building at one-tenth proportion, every measurement is exactly one-tenth the size of the real thing.

The word also describes whether something seems appropriately sized or fair. A pair of pants might be out of proportion if the legs are too short for the waist. When someone says a punishment is out of proportion to the crime, they mean it's too harsh for what actually happened: getting grounded for a month because you forgot to make your bed once would be way out of proportion.

Things in proportion feel balanced and right. Things out of proportion feel mismatched or extreme.