Proportion examines ratio or the quantitative comparison between two similar objects. In mathematical proportion, there are three different types that distinguishes proportion: geometric, arithmetic, and harmonic. Geometric proportion is when an object is multiplied by x factor, yet the same ratios remain between the objects, while arithmetic is the change by adding a certain amount. All have characteristics with a constant ratio creates proportion and a principle of unity. (Grove Art Online) -Leah Houston

Proportion in art is the comparative concurring relationship between two or more elements in a composition concerning size, color, quantity, degree, and ratio. This relationship between two elements of the work of art is harmonious when a "correct" or desirable relationship exists between them. Correct sizing and distribution of an element or object are generally what creates good proportion. Good proportion adds symmetry or balance among the parts of a design as a whole. Symmetry and balance are pleasing to the eye and allow the spectator to view the work of art as comprehensible and communicative. Proportion is usually not even noticed until something is out of proportion. When the relative size of two elements being compared seems wrong or out of balance it is said to be "out of proportion". (Pattie Umali)