Economies of scale

Economies of scale and diseconomies of scale refer to an economic property of production that affects cost if quantity of all input factors are increased by some amount. If costs increase proportionately, there are no economies of scale; if costs increase by a greater amount, there are diseconomies of scale; if costs increase by a lesser amount, there are positive economies of scale. When combined, economies of scale and diseconomies of scale lead to ideal firm size theory, which states that per-unit costs decrease until they reach a certain minimum, then increase as the firm size increases further.
Economies of scale refers to the decreased per unit cost as output increases.