What Is the Marginal Revenue Formula? A Guide for Business Owners

Deciding whether to produce and sell one more unit, hire one more employee, or take on one more client comes down to a single question: does that next unit bring in more than it costs? Marginal revenue is the tool that answers the revenue half of that equation, and it works alongside marginal cost to point to the output level where growth stops adding profit. This guide covers the formula, a worked example, and how small business owners can put it to use.

What Is Marginal Revenue?

Marginal revenue is the change in total revenue that results from selling one additional unit of output. It answers a specific question: if a business sells one more unit, how much more revenue does that bring in?

For businesses operating in competitive markets where price is fixed, such as commodity sellers, marginal revenue equals the price of the product. For businesses with pricing power, marginal revenue typically declines as output increases, because selling more units often requires lowering the price.

Marginal revenue is most useful in combination with marginal cost. The relationship between the two tells a business owner whether producing and selling the next unit is worth it.

The Marginal Revenue Formula

Marginal Revenue equals Change in Total Revenue divided by Change in Quantity Sold, written as:

MR = Delta TR / Delta Q

Delta TR is the change in total revenue between two output levels, and Delta Q is the change in the number of units sold, typically one unit when calculating for a single additional sale. This formula is consistent across business types and industries. What changes is how price responds to volume in a given market.

How to Calculate Marginal Revenue: A Worked Example

A small bakery sells 100 loaves of bread per week at $5 each, for total revenue of $500. The owner considers producing 101 loaves and dropping the price to $4.98 to move the extra unit.

New total revenue comes to 101 loaves multiplied by $4.98, or $502.98. The change in total revenue is $502.98 minus $500.00, or $2.98, and the change in quantity is 1 unit. Marginal revenue is $2.98 divided by 1, or $2.98.

The 101st loaf generates $2.98 in additional revenue, even though it sells for $4.98, because the price reduction applies to all units sold. This is why marginal revenue is often lower than price in markets where the seller must reduce price to sell more.

Marginal Revenue vs. Marginal Cost

Marginal cost is the additional cost of producing one more unit, including materials, labor, and any other variable inputs. The profit-maximizing output level is where marginal revenue equals marginal cost. At that point, the last unit produced adds exactly as much to revenue as it adds to cost, so producing more would reduce profit.

If marginal revenue exceeds marginal cost, producing more increases profit. If marginal cost exceeds marginal revenue, producing more reduces it. For business owners, keep expanding output as long as each additional unit brings in more than it costs to produce, and stop when those numbers converge.

Why Marginal Revenue Matters for Small Businesses

Marginal revenue shows up in several everyday small business decisions, not just formal economic analysis.

• Pricing Decisions: A volume discount or promotional price should be evaluated by what the additional sale is actually worth, net of any price concession applied across existing volume.
• Hiring Decisions: If adding a staff member allows a business to produce and sell more units, comparing the marginal revenue of those units to the marginal cost of the hire shows whether the hire adds profit.
• Service Capacity: For service businesses, the same logic applies to additional clients, appointments, or contracts, since each additional unit of output should add more revenue than it costs to deliver.
• Identifying Diminishing Returns: When marginal revenue starts declining toward marginal cost, that is a signal to hold volume, raise prices, or reduce costs rather than push for more output.

Applied consistently, marginal revenue turns a gut feeling about growth into a number a business owner can act on.