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Understanding Minimum Efficient Scale

Aug 6, 2025

Overview

This lecture explains minimum efficient scale (MES), its impact on firm competitiveness, and how MES relates to market concentration and market structure.

Minimum Efficient Scale (MES)

  • MES is the smallest production scale at which long-run average total costs stop declining.
  • Firms at MES have realized all economies of scale and operate most efficiently.
  • If a firm produces less than MES, it has higher average costs and is less competitive.
  • MES ensures firms can remain profitable even if market prices fall, unlike less efficient competitors.

MES and Market Size

  • Market size refers to total demand, e.g., all tacos sold daily in a city.
  • When MES is a small fraction of total market size, many firms can operate efficiently.
  • Multiple firms at MES lead to a fragmented market with many competitors.
  • When MES is a large fraction of market size, only a few firms can reach MES, resulting in a concentrated market.

Market Concentration and Structure

  • Fragmented markets have many competitors, each with a small market share.
  • Concentrated markets have few firms, each controlling a large portion of the market.
  • If MES equals or exceeds total market size, only one firm can operate efficiently, leading to a natural monopoly.

Key Terms & Definitions

  • Minimum Efficient Scale (MES) — The lowest level of output at which a firm's long-run average total cost stops decreasing.
  • Economies of Scale — Cost advantages obtained with increased output.
  • Market Concentration — The degree to which a small number of firms control a large market share.
  • Fragmented Market — A market with many small competitors.
  • Natural Monopoly — A market where one firm can supply the entire market most efficiently due to high MES.

Action Items / Next Steps

  • Review the relationship between MES and different market structures.
  • Practice applying these concepts to other industries or example markets.