Consumer Surplus

Consumer surplus is the surplus of quantity that consumers are willing and able to buy at a given price, above the quantity that they actually buy. In other words, it is the difference between the quantity of a good that consumers are willing to buy at a given price and the quantity that they are actually able to afford to buy.

Explanation:

• Demand curve: The demand curve shows the relationship between the price of a good and the quantity that consumers are willing to buy.
• Quantity supplied: The quantity supplied is the quantity of a good that producers are willing and able to produce at a given price.
• Equilibrium quantity: The equilibrium quantity is the quantity where the quantity supplied equals the quantity demanded.
• Consumer surplus: The consumer surplus is the area below the demand curve and above the equilibrium quantity.

Formula:

Consumer Surplus = [Qd - Qs] * P

where:

• Qd is the quantity demanded
• Qs is the quantity supplied
• P is the price of the good

Example:

In the graph below, the demand curve is represented by the blue line, the quantity supplied is represented by the red line, and the equilibrium quantity is represented by the point E. The consumer surplus is the area below the demand curve and above the equilibrium quantity, which is shaded in green.

[Image of a demand curve, quantity supplied, equilibrium quantity, and consumer surplus]

The consumer surplus in this example is:

Consumer Surplus = [Qd - Qs] * P = [200 - 100] * 20 = 2000

Therefore, the consumer surplus is 2000 units.

Significance:

• Consumer surplus is an important concept in microeconomics because it helps to explain how markets clear and how prices are determined.
• Consumer surplus measures the efficiency of a market.
• Consumer surplus is a measure of consumer welfare.