# Marginal Revenue - MR

## What is 'Marginal Revenue - MR'

Marginal revenue is the increase in revenue that results from the sale of one additional unit of output. While marginal revenue can remain constant over a certain level of output, it follows the law of diminishing returns and will eventually slow down, as the output level increases. Perfectly competitive firms continue producing output until marginal revenue equals marginal cost.

## BREAKING DOWN 'Marginal Revenue - MR'

A company calculates marginal revenue by dividing the change in total revenue by the change in total output quantity. Therefore, the sale price of a single additional item sold will equal marginal revenue. For example, a company sells 100 items for a total of \$1,000. If it sells the next item for \$8, the marginal revenue of the 101st item is \$8. Marginal revenue disregards the previous average price of \$10, as it only analyzes the incremental change.

## Marginal Revenue Equaling Marginal Cost

A company experiences best results when production and sales continue until marginal revenue equals marginal cost. Marginal cost is the total expense of selling one additional good. If marginal revenue exceeds marginal costs, this indicates the company made a profit on the item sold. When marginal revenue falls below marginal cost, this is an indicator that it is no longer profitable to produce and sell this good.

## Competitive Firms vs. Monopolies

Marginal revenue for competitive firms is typically constant. This is because the market dictates the optimal price level and companies do not have much – if any – discretion over the marginal price. Marginal revenue works differently for monopolies. Because monopolies have control over the quantity of available goods in the market, marginal revenue for a monopoly decreases as additional goods are sold, because the level of goods being supplied is increasing.

## Marginal Revenue vs. Average Revenue

The average cost is the total revenue earned divided by the total units. A competitive firm’s marginal revenue always equals its average revenue and price. This is because the price remains constant. In a monopoly, because the price changes as the quantity sold changes, marginal revenue diminishes and will always be equal to or less than average revenue.

## Revenue Schedule

To assist with the calculation of marginal revenue, a revenue schedule outlines the total revenue earned as well as the incremental revenue for each unit. The first column of a revenue schedule lists the projected quantities demanded in increasing order, and the second column lists the corresponding market price. The product of these two columns results in projected total revenues. The difference between the total projected revenue of one line item and the total projected revenue from the line below it is the marginal revenue of the bottom line. For example, 10 units sell at \$9 each results in total revenue of \$90, while 11 units sell at \$8.50 results in total revenue of \$93.50. This indicates the marginal revenue of the 11th unit is \$3.50.