What Is the Best Definition of Marginal Revenue?
Marginal revenue is the extra revenue a business earns from selling one additional unit of a product or service.
The Best Definition
The best definition of marginal revenue is this: marginal revenue is the additional revenue a business earns from selling one more unit of a good or service.
The basic formula is:
Marginal Revenue = Change in Total Revenue / Change in Quantity Sold
If a company sells one more item and total revenue increases by $20, the marginal revenue of that item is $20.
Marginal revenue tells a business how much extra money the next sale adds.
Why Marginal Revenue Matters
Businesses use marginal revenue to decide whether selling more units is worth it. More sales are not automatically better if the extra revenue is less than the extra cost.
For example, a bakery may sell more cupcakes by lowering the price. But if the lower price reduces revenue too much, producing more may not help profit.
Marginal revenue helps answer: should we increase output, reduce output, or keep production the same?
Simple Example
Suppose a business sells 10 notebooks and earns $100 in total revenue. Then it sells 11 notebooks and earns $108 in total revenue.
The marginal revenue of the 11th notebook is $8 because total revenue increased by $8.
| Quantity sold | Total revenue | Marginal revenue |
|---|---|---|
| 10 notebooks | $100 | Not shown |
| 11 notebooks | $108 | $8 |
| 12 notebooks | $115 | $7 |
Marginal revenue can change from one unit to the next.
Marginal Revenue vs. Total Revenue
Total revenue is all the money earned from sales. Marginal revenue is only the extra revenue from selling one more unit.
This difference matters because total revenue may rise while marginal revenue falls. A business may sell more units, but each additional unit may add less revenue than the previous one.
In competitive markets, marginal revenue may equal the market price. In less competitive markets, a business may need to lower price to sell more, which can reduce marginal revenue.
Marginal Revenue vs. Profit
Marginal revenue is not the same as profit. Revenue looks at money coming in. Profit subtracts costs.
If the marginal revenue from selling one more product is $15 but the marginal cost of producing it is $10, the extra unit adds $5 before considering other factors. If marginal cost is $18, selling that extra unit may reduce profit.
This is why marginal revenue is usually studied with marginal cost.
Marginal Revenue and Marginal Cost
Profit-maximizing firms often compare marginal revenue and marginal cost. A common economics rule says production should continue while marginal revenue is greater than marginal cost.
When marginal revenue equals marginal cost, the business may be near the most profitable output level. Producing beyond that point may add more cost than revenue.
Quick question: does marginal revenue always go down?
Not always, but it often decreases when a business must lower prices to sell additional units.
Why Prices Affect Marginal Revenue
If a business can sell every extra unit at the same price, marginal revenue may stay constant. But if it must lower the price to attract more buyers, the revenue from extra units can fall.
For example, a company may sell 100 tickets at $50 each. To sell more, it may reduce the price to $45. That discount affects not only the extra buyers but sometimes the total revenue pattern.
This is why pricing decisions require careful math.
Common Mistakes
One mistake is thinking marginal revenue means average revenue. Average revenue is total revenue divided by quantity sold. Marginal revenue is the change caused by one more unit.
Another mistake is assuming more revenue always means more profit. A business can increase revenue and still lose money if costs rise faster.
A third mistake is forgetting that marginal revenue can be negative. If a company cuts price so much that total revenue falls after selling more units, the extra sale has reduced revenue instead of increasing it. That is a warning sign that the pricing strategy may be hurting the business.
A Strong Student-Friendly Definition
For schoolwork, you can write: Marginal revenue is the extra revenue earned from selling one additional unit of output.
That definition is clear and correct. To make it stronger, include the formula and explain that businesses compare marginal revenue with marginal cost when making production decisions.