Consumer surplus (CS) is the difference between what a buyer is willing to pay for a good or service and what they actually pay (Mankiw, 2024). It measures the additional benefit, in dollars, that consumers receive when purchasing a good or service at the market price.
There are several key points to consider when determining consumer surplus. First, consider the amount the consumer is willing to pay for the product or service. Then, consider the market price of the good or service. As long as the consumer is willing to pay more than the market price, there is a consumer surplus.
Formula
Consumer surplus (CS) = Willingness to Pay – Market Price
Consider an individual consumer, Steve. Steve wants to purchase a ticket to an upcoming concert for his favorite artist. He is willing to pay $120 for a ticket. When ticket sales are announced, the market price is $75. Steve purchases a ticket because the market price is lower than the amount he is willing to pay.
Steve’s consumer surplus is the difference between his willingness to pay of $120 and the market price of $75.
Steve’s Consumer Surplus:
$120 − $75 = $45
Therefore, Steve’s consumer surplus is $45.
Calculating Total Consumer Surplus
Now that you can calculate an individual consumer’s surplus, how do you calculate the total consumer surplus for a group of consumers?
To determine the total consumer surplus, add the consumer surplus of each consumer in the group.
Formula
Total CS = CS of consumer(1) + CS of consumer(2) + […] +CS of consumer(n)
Now consider three consumers: Steve, Mary, and Todd. All three would like to purchase a ticket to the concert. Their willingness to pay differs:
Steve’s willingness to pay: $120
Mary’s willingness to pay: $60
Todd’s willingness to pay: $90
Recall that the market price is $75.
Steve:
$120 − $75 = $45 consumer surplus
Todd:
$90 − $75 = $15 consumer surplus
Mary:
Mary’s willingness to pay is $60, which is less than the market price of $75. Therefore, she does not purchase a ticket, and her consumer surplus is $0.
Mankiw, N. G. (2024). Principles of Economics. Cengage Learning.
Tip: To identify consumer surplus, compare the price a consumer is willing to pay with the market price. If their willingness to pay is higher, the difference represents their consumer surplus.
Need More Help?
Want additional support? Sign up for our group sessions. Take a look at the full workshop schedule. For help signing up and accessing the Academic Support Center, see the How to Book ASC Sessions Page.