cost

Cost is the monetary value of goods and services purchased by producers and consumers. For example, a consumer typically equates cost with the price of a good (such as a loaf of bread, a pair of shoes, or a car) or a service (such as a haircut or a night in a hotel). For a manufacturer or service provider, cost (i.e., input cost) is the amount of money spent to produce something, and is subtracted from the revenue earned from selling the good or service to determine the profit.

Consider the case of a bicycle manufacturer. Suppose, on a given day, the cost of all the bike components, the use of the tools and machinery, the lease on its buildings, and all the labor used to produce bicycles, totals $12,900. On that day the manufacturer produces 100 bicycles.

Here are several ways in which economists and accountants might measure cost:

Total cost and average cost. The total cost—that is, the overall amount spent to make a certain amount of product—is $12,900. To get the average cost per bicycle, divide the total cost ($12,900) by the number of bicycles made (100). The average cost would be $129.

Fixed and variable costs. Some costs—like the cost of rent or heavy machinery—don’t change based on how many bicycles are produced. These are called fixed costs. Other costs, like labor and raw materials, can increase or decrease depending on how much is produced. These are called variable costs.

So if an hourly employee doesn’t report for work one day, the variable costs might be lower, but the fixed costs would be the same. Most likely, the day’s output would be fewer than 100 bicycles; the total cost would be lower as well, but the average cost per bicycle produced would be higher because of the fixed costs.

Marginal cost. Another important idea in economic analysis is marginal cost, or the extra cost of producing an additional unit. A business that wants to maximize its profit will continue making products until the cost of making an additional unit (marginal cost) equals the additional profit from selling it (marginal revenue).

To learn more about fixed, variable, and marginal cost—and other economic theory terms—read the theory of production entry on Britannica.

Opportunity cost. Whenever you choose to spend money on a good or a service, you’re also choosing not to spend that money on something else. Opportunity cost is the value of other goods, services, or activities you give up when you choose one investment or activity over another.

For example, if you were to splurge on a Mediterranean cruise, the opportunity cost might be a new car that you were saving up to buy. If you buy shares of stock, your opportunity cost might be the guaranteed interest you’d receive on a certificate of deposit. If the bicycle manufacturer was trying to choose between making bicycles and skateboards, the opportunity cost of making bicycles would be the revenue they could receive from making skateboards instead.

Opportunity cost is how we measure one expenditure over another.

Externalities. Another aspect of cost concerns externalities, or costs imposed on others—intentionally or unintentionally. For example, the cost of generating electricity by burning high-sulfur coal may go beyond the price and transportation of coal and the fixed and variable costs of operating the power plant. Externalities include the costs associated with air pollution, such as medical costs, reduced productivity due to poor air quality, and damage to crops and farmland.