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Long Run Average Cost




The long run average cost (LRAC or LAC) curve illustrates - for a given quantity of production - the average cost per unit which a faces in the Long Run (i.e. when no Factors Of Production are fixed).

LRAC curve is derived from a series of short run average cost curves. It is also called the 'envelope curve' since it envelops all the short run average cost curves.

In Perfect Competition , the LRAC curve is flat, at the point of equilibrium- there are Constant Returns To Scale . Typical LRACs are U-shaped, which means that up to a certain optimum point, there are Economies Of Scale , and as production increases beyond this, there are diseconomies of scale. LRAC are generally flatter than short run average cost curve.

In some industries, the LRAC is L-shaped, and economies of scale increase indefinitely. This means that the largest firm tends to have a cost advantage, and the industry tends naturally to become a monopoly, and hence is called a Natural Monopoly . Natural monopolies tend to exist in industries with high capital costs in relation to variable costs, such as Water Supply and Electricity Supply .


SEE ALSO



The difference between long run and short run to be understood first.