In economics, output elasticity is the percentage change of output (GDP or production of a single firm) divided by the percentage change of an input. It is sometimes called partial output elasticity to clarify that it refers to the change of only one input. As with every elasticity, this measure is defined locally, i.e. defined at a point. A different usage of the term "output elasticity" is defined as the percentage change in output per one percent change in all the inputs. The coefficient of output elasticity can be used to estimate returns to scale.