Economies of Scale

Economies of scale characterizes a production process in which an increase in the scale of the firm causes a decrease in the long run average cost of each unit. Economies of scale can be enjoyed by any size firm expanding its scale of operation. The common ones are purchasing (bulk buying of materials through long-term contracts), managerial (increasing the specialization of managers), financial (obtaining lower-interest charges when borrowing from banks and having access to a greater range of financial instruments), marketing (spreading the cost of advertising over a greater range of output in media markets). Each of these factors reduces the long run average costs (LRAC) of production by shifting the short-run average total cost (SRATC) curve down and to the right.
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In economics, returns to scale and economies of scale are related terms that describe what happens as the scale of production increases. They are different terms and are not to be used interchangeably.
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The decrease in the marginal cost of production as a firm's scale of operations increases.

reductions in the price per unit of marketing or manufacturing a product as the quantity marketed or produced increases.

Cost reductions or productivity efficiencies achieved through size-optimization in relation to operational circumstances. For example, commodity freight rates usually decline as the volume of cargo tonnage shipped increases. (MARAD1)