Excess Capacity
What is Excess Capacity?
Excess capacity occurs when a firm produces less than the quantity that minimizes average total cost.
In monopolistic competition, firms produce at a point where demand is tangent to ATC but to the left of the minimum ATC, leading to underutilized resources. This results from product differentiation and the need to maintain some market power.
Excess Capacity: a worked example
A neighborhood coffee bar in long run monopolistic competition sells 240 cups a day at $4.00, and its average total cost at that output is also $4.00, so total revenue and total cost both equal $960 and economic profit is zero. Its ATC curve bottoms out at $3.40 when output reaches 400 cups. The gap of 400 - 240 = 160 cups a day is the excess capacity: the shop is equipped and staffed for output it never produces. Each cup costs $4.00 - $3.40 = $0.60 more to make than it would at the efficient scale, and across 240 cups that is 240 x $0.60 = $144 a day of resources a shop running at its lowest cost output would not have spent.
The mistake students make with excess capacity
Excess capacity gets read as sloppiness, as though the shop could simply brew 400 cups and pocket the lower average cost. Its demand curve slopes down, so selling 160 more cups a day requires cutting the price, and at 400 cups the price buyers would pay sits below the $3.40 average total cost, turning zero profit into a loss. The firm is already maximizing profit where marginal revenue equals marginal cost. Excess capacity is the standing result of product differentiation in this market structure, not an oversight by the owner, and it is why the outcome counts as productively inefficient even in long run equilibrium.
Excess Capacity questions
Why do monopolistically competitive firms have excess capacity?
Product differentiation gives each firm a downward sloping demand curve, and a downward sloping line can only be tangent to a U shaped average total cost curve along its falling section, which lies to the left of minimum ATC. Long run entry pushes each firm's demand leftward until that tangency is reached and economic profit hits zero. The firm therefore settles at an output below the one that would minimize average cost, and the difference is the excess capacity.
Does excess capacity mean the firm is losing money?
Excess capacity and zero economic profit sit together in long run equilibrium, so the firm covers every explicit and implicit cost including a normal return to the owner. Price equals average total cost at the chosen output, though not the lowest possible average total cost. A genuine loss would require price below ATC, which triggers exit rather than the stable tangency that defines this long run outcome.
Do perfectly competitive firms have excess capacity?
Perfectly competitive firms have none. Their demand curve is horizontal at the market price, so in long run equilibrium that flat line is tangent to average total cost exactly at its minimum point and output sits at the efficient scale. Productive efficiency holds, price equals minimum ATC, and price also equals marginal cost. The contrast with monopolistic competition is a standard free response comparison, so the tangency argument is worth being able to draw from memory.
Formula / Example
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Related terms
Common comparisons
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