Diagram of Perfect Competition

Perfect competition is a market structure with:

  • Freedom of entry and exit
  • Perfect information/knowledge
  • Many firms
  • The price is set by the industry supply and demand.
  • Firms are price takers; this means their demand curve is perfectly elastic. If they set a higher price, nobody would buy because of perfect knowledge. Therefore firms have an elastic demand curve.
  • In the long run firms in perfect competition will make normal profits.

Diagram Perfect Competition


  • The market price is set by the supply and demand of the industry (diagram on right)
  • This sets market equilibrium price of P1.
  • A firm maximises profit at Q1 where MC = MR

Changes in Perfect Competition equilibrium

Market demand rises from D1 to D2 causing the price to rise from P1 to P2. This causes supernormal profit.



Perfect competition in long run



However, the supernormal profit encourages more firms to enter the market. New firms enter (supply increases from S1 to S2) until the price falls to P1 and normal profits are made once again.

Effect of fall in demand

If there was a fall in market demand, the price would fall. Now firms would make a loss, and some will go out of business causing the supply curve to shift to the left. The supply curve will fall until price rises back to a level which gives normal profit.

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By on January 14th, 2017

21 thoughts on “Diagram of Perfect Competition

  1. I have need only perfect compition in short run normal profit, super normal profit, loss super or super normal losss with daigrams and features and in real life use of perfect competition short run

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