What is the difference between marginal cost and marginal revenue? Marginal cost is the additional expense of producing one more unit, while marginal revenue is the additional income generated by selling one more unit.
Businesses compare these figures to determine whether increasing production will improve profit. When marginal revenue is higher than marginal cost, another unit adds to profit. When marginal cost is higher, another unit reduces profit. Under standard economic conditions, profit is maximized where marginal revenue equals marginal cost or at the nearest feasible production level.
For business owners asking, “What is the difference between marginal cost and marginal revenue?”, comparing both figures provides a practical way to evaluate production, pricing and profitability decisions.
Quick Answer
What is the difference between marginal cost and marginal revenue? The difference between marginal cost and marginal revenue is straightforward:
- Marginal cost, or MC: The change in total cost caused by additional output.
- Marginal revenue, or MR: The change in total revenue caused by additional sales.
- Marginal profit: Marginal revenue minus marginal cost.
The basic decision rule is:
- MR > MC: Increasing output can raise profit.
- MR = MC: Output may be at the profit-maximizing level.
- MR < MC: Increasing output can reduce profit.
The MR = MC rule identifies the optimal output under standard assumptions, but it does not automatically mean that the company is breaking even.
Key Takeaways
To understand what is the difference between marginal cost and marginal revenue?, consider how each figure affects the next unit of production and profit.
- Marginal cost focuses on the expense side of the next unit.
- Marginal revenue focuses on the income side of the next unit.
- Marginal figures are different from average cost, total cost, price and total revenue.
- When MR exceeds MC, another unit adds to total profit.
- When MC exceeds MR, another unit reduces total profit.
- MR = MC identifies the profit-maximizing output under standard assumptions.
- MR = MC does not necessarily mean the company is breaking even.
- Market structure affects marginal revenue more directly than marginal cost.
- Accurate marginal analysis requires realistic data about pricing, demand, labor, materials, capacity and operating constraints.
What Does “Marginal” Mean in Economics?
To understand What is the difference between marginal cost and marginal revenue, it is first important to understand what the word “marginal” means in economics.
- In economics, the word “marginal” refers to the effect of a small additional change.
- Instead of asking how much it costs to produce all units, marginal analysis asks:
- How much will total cost change if the business produces one more unit?
- Instead of asking how much total revenue the company earns, it asks:
- How much will total revenue change if the company sells one more unit?
This focus on the next unit helps decision-makers evaluate whether expanding production, accepting another order, serving another customer or adding another subscription will improve profit.
Marginal analysis is especially useful because average figures can hide important changes. A product may have a profitable average selling price but become unprofitable at the margin if overtime, discounts, expedited shipping or production bottlenecks make the next unit unusually expensive.
The question “What is the difference between marginal cost and marginal revenue?” focuses on comparing the additional expense with the additional income.
What Is Marginal Cost?
Marginal cost is the increase in total cost caused by producing an additional unit of output.
OpenStax defines marginal cost as the additional cost of producing one more unit and calculates it by dividing the change in total cost by the change in quantity.
Marginal cost provides the expense side of the answer to What is the difference between marginal cost and marginal revenue?
Marginal Cost Formula
The standard formula is:
Marginal Cost = Change in Total Cost ÷ Change in Quantity
Or:
MC = ΔTC ÷ ΔQ
Where:
- MC = marginal cost
- ΔTC = change in total cost
- ΔQ = change in quantity produced
- Δ means “change in”
When quantity changes by exactly one unit, marginal cost is simply the difference between the new total cost and the previous total cost.
Simple Marginal Cost Example
Suppose a company’s total cost is:
- Total cost of producing 100 units: $2,500
- Total cost of producing 101 units: $2,528
The marginal cost of the 101st unit is:
MC = ($2,528 − $2,500) ÷ (101 − 100)
MC = $28
Producing the 101st unit adds $28 to the company’s total cost.
Marginal Cost for a Batch of Units
Companies often calculate marginal cost across a batch rather than a single item.
Suppose:
- Total cost at 1,000 units: $18,000
- Total cost at 1,100 units: $20,500
The additional 100 units increase total cost by $2,500.
MC = ($20,500 − $18,000) ÷ (1,100 − 1,000)
MC = $2,500 ÷ 100
MC = $25 per additional unit
The estimated marginal cost for that production range is $25 per unit.
Which Expenses Are Included in Marginal Cost?
When answering “What is the difference between marginal cost and marginal revenue?” it is important to identify the expenses that influence marginal cost.
Marginal cost should include expenses that change because the business produces additional output. Depending on the business, these may include the following:
- Raw materials
- Direct labor
- Packaging
- Sales commissions
- Transaction-processing fees
- Shipping expenses
- Additional electricity or machine usage
- Temporary workers
- Overtime wages
- Product-specific royalties
- Incremental customer-support costs
- Additional cloud-computing usage
- Spoilage or return allowances
- Incremental quality-control expenses
Fixed expenses are not automatically included merely because the business has them.
For example, monthly rent may remain unchanged whether a factory produces 1,000 or 1,001 units. In that situation, the next unit does not create additional rent, so rent does not affect the marginal cost of that unit.
However, a normally fixed expense can become relevant when increased production crosses a capacity threshold. If producing additional units requires renting another warehouse, buying a machine or hiring a supervisor, that entire step cost must be considered in the expansion decision.
Understanding which expenses change with output provides important context for the question: What is the difference between marginal cost and marginal revenue?
Which Costs Should Be Included in a Marginal Decision?
A marginal decision should include relevant costs—costs that will change depending on whether the business produces or sells the additional output.
Relevant costs may include:
- Additional materials and labor
- Overtime premiums
- Avoidable shipping or fulfillment expenses
- Additional equipment rental
- Incremental software or cloud usage
- Lost contribution from another product
- A capacity cost triggered by the expansion
Businesses should distinguish three important cost categories.
Sunk Costs
A sunk cost has already been incurred and cannot be recovered. Because the decision cannot change it, it should not affect whether another unit is produced.
For example, money already spent on completed market research is normally irrelevant to the next production decision.
Avoidable Costs
An avoidable cost will disappear if a product, order or activity is not pursued. Avoidable costs are relevant because the decision directly changes them.
Opportunity Costs
An opportunity cost is the value sacrificed by choosing one alternative over another.
Suppose a factory has enough capacity to produce either Product A or Product B. Even if Product A has a low direct marginal cost, producing it may be a poor decision when it displaces a more profitable sale of Product B.
Not every fixed cost is a sunk cost. A warehouse lease that can be cancelled, a supervisor who must be hired or equipment that can be rented only for the expansion may be fixed over a particular output range but still relevant to the decision.
These relevant costs strengthen a business owner’s understanding of What is the difference between marginal cost and marginal revenue? by showing which additional expenses should be compared with the revenue generated by extra output.
Why Does Marginal Cost Change?
Understanding why marginal cost changes is important when answering What is the difference between marginal cost and marginal revenue?
Marginal cost is not always constant.
It may initially decline when workers become more efficient, machinery is used more effectively or suppliers provide volume discounts. It may later rise because of overtime, congestion, equipment limitations, material shortages or diminishing marginal productivity.
Standard short-run cost models often show an upward-sloping marginal cost curve after an initial low-cost range. OpenStax explains that diminishing marginal returns can make additional units progressively more expensive to produce.
A business should therefore avoid assuming that the average historical cost equals the cost of its next unit.
Changes in production cost provide additional context for What is the difference between marginal cost and marginal revenue? because rising marginal cost can change whether another unit remains profitable.
Short-Run vs. Long-Run Marginal Cost
Marginal cost depends partly on the period being analyzed.
Short-Run Marginal Cost
In the short run, at least one production input is fixed. A company may be unable to immediately expand its factory, replace machinery or change a long-term contract.
As output increases within those limits, marginal cost may rise because of:
- Overtime
- Machine congestion
- Reduced worker productivity
- Expedited materials
- Maintenance pressure
- Limited storage capacity
Long-Run Marginal Cost
In the long run, the business can change all major inputs. It may build another facility, install more efficient equipment, renegotiate supplier agreements or redesign its production process.
The marginal cost of long-term expansion may therefore differ substantially from the cost of squeezing additional output from the current operation.
For example, producing another 10,000 units in the existing factory may require expensive overtime. Building a larger facility could lower the ongoing cost of those units, although the investment and financing costs must also be considered.
Managers should match the marginal-cost estimate to the decision’s time horizon. Short-run data should not automatically be used to evaluate a permanent capacity expansion.
This time-based comparison also supports a clearer answer to What is the difference between marginal cost and marginal revenue? because the relevant marginal cost may change depending on whether the company is making a short-term production decision or a long-term expansion decision.
What Is Marginal Revenue?
Understanding marginal revenue is essential when answering What is the difference between marginal cost and marginal revenue?
Marginal revenue is the additional revenue earned from selling another unit of a good or service.
OpenStax defines marginal revenue as the additional revenue gained from selling one more unit.
Marginal Revenue Formula
The formula is:
Marginal Revenue = Change in Total Revenue ÷ Change in Quantity Sold
Or:
MR = ΔTR ÷ ΔQ
Where:
- MR = marginal revenue
- ΔTR = change in total revenue
- ΔQ = change in quantity sold
Discrete Marginal Values vs. Calculus Derivatives
Marginal cost and marginal revenue can be calculated in two related ways.
When a business uses actual accounting data, it normally calculates a discrete change:
MC = ΔTC ÷ ΔQ
MR = ΔTR ÷ ΔQ
These formulas measure the average marginal cost or revenue across a specific increase in output, such as 10, 100 or 1,000 additional units.
When total cost and total revenue are represented by smooth mathematical functions, marginal values are calculated using derivatives:
MC(Q) = dTC/dQ
MR(Q) = dTR/dQ
A derivative measures the instantaneous rate at which cost or revenue changes at a particular output level. For products sold only in whole units, the derivative is usually interpreted as an approximation of the cost or revenue associated with the next unit.
This distinction matters because the marginal cost calculated across a batch may hide differences between individual units. If the cost of producing each additional unit rises sharply within the batch, managers should examine smaller output intervals before making a decision.
This comparison helps clarify What is the difference between marginal cost and marginal revenue? because marginal cost measures the added production expense, while marginal revenue measures the added income from the resulting sale.
Simple Marginal Revenue Example
Suppose a company earns:
- Total revenue from 100 units: $4,500
- Total revenue from 101 units: $4,540
The marginal revenue from selling the 101st unit is:
MR = ($4,540 − $4,500) ÷ (101 − 100)
MR = $40
The 101st unit adds $40 to total revenue.
If its marginal cost is $28, then the unit contributes:
Marginal profit = MR − MC
Marginal profit = $40 − $28
Marginal profit = $12
Producing and selling that unit increases total profit by $12, assuming the estimates are accurate and no other relevant costs are omitted.
Is Marginal Revenue Always Equal to Price?
No. Marginal revenue equals price only under particular market conditions.
Marginal Revenue Under Perfect Competition
A perfectly competitive company is a price taker. It can sell another unit at the existing market price without reducing the price of its previous units.
Therefore:
MR = Price
If the market price is $25 and every additional unit can be sold for $25, marginal revenue is also $25. OpenStax explains that a perfectly competitive firm’s marginal revenue equals the market price because each additional sale increases revenue by that same price.
Marginal Revenue When a Business Has Pricing Power
A company with market power may need to lower its price to sell additional units. The lower price may apply not only to the new unit but also to units it was already selling.
As a result, the additional revenue generated by increasing sales can be lower than the new selling price.
For a monopolist facing a downward-sloping demand curve, marginal revenue lies below the demand curve because selling a higher quantity generally requires lowering the price. That lower price affects revenue from earlier units as well as the additional unit.
How Demand Elasticity Affects Marginal Revenue
For a company with pricing power, marginal revenue is closely connected to the price elasticity of demand.
Using the convention that demand elasticity is expressed as a negative number:
MR = P × (1 + 1/Ed)
Where:
- MR = marginal revenue
- P = price
- Ed = price elasticity of demand
The relationship produces three general outcomes:
- Elastic demand: Marginal revenue is positive.
- Unit-elastic demand: Marginal revenue is zero, and total revenue is at its maximum.
- Inelastic demand: Marginal revenue is negative.
Understanding what is the difference between marginal cost and marginal revenue? also requires examining how demand elasticity influences pricing and output decisions.
A single-price company facing a downward-sloping demand curve and positive marginal cost would not normally choose an output in the inelastic portion of demand. In that region, reducing quantity and raising price can increase total revenue while reducing total cost.
This conclusion applies most directly to a business charging one price to all customers. More complex pricing models, including price discrimination, subscriptions, bundles and multiproduct pricing, may produce different marginal-revenue relationships.
The elasticity relationship also explains why maximizing total revenue is different from maximizing profit. Total revenue reaches its maximum where marginal revenue equals zero, while profit is generally maximized where marginal revenue equals marginal cost.
A firm with market power normally determines its profit-maximizing quantity where MR = MC and then uses the demand curve to identify the price customers will pay for that quantity.
Marginal Revenue Example With a Price Reduction
Suppose a company can sell:
- 10 units at $50 each
- 11 units only if it reduces the price to $47 for every unit
Total revenue at 10 units is:
10 × $50 = $500
Total revenue at 11 units is:
11 × $47 = $517
Marginal revenue is:
MR = $517 − $500
MR = $17
Although the eleventh unit sells at a listed price of $47, marginal revenue is only $17. The business receives $47 from the extra unit but loses $3 of revenue on each of the first 10 units because of the price reduction.
Revenue gained from the new unit:
$47
Revenue lost on the first 10 units:
10 × $3 = $30
Net change in revenue:
$47 − $30 = $17
This is why price and marginal revenue should not be treated as identical when the business must change its overall price to increase sales.
What Is the Difference Between Marginal Cost and Marginal Revenue?
The clearest way to understand marginal cost vs. marginal revenue is to compare what each one measures.
| Area | Marginal Cost | Marginal Revenue |
| Meaning | Additional cost of producing more output | Additional revenue from selling more output |
| Abbreviation | MC | MR |
| Formula | Change in total cost ÷ change in quantity | Change in total revenue ÷ change in quantity |
| Main focus | Expenses | Income |
| Based on | Total cost | Total revenue |
| Common influences | Materials, labor, capacity and productivity | Price, demand, discounts and market structure |
| Business question | What will the next unit cost? | How much revenue will the next unit generate? |
| Effect on profit | Reduces profit when it rises, all else equal | Increases profit when it rises, all else equal |
| Decision rule | Compare MC with MR | Compare MR with MC |
| Profit-maximizing relationship | Produce until MC reaches MR | Produce until MR reaches MC |
Marginal cost and marginal revenue are not competing calculations. They are complementary measurements that should normally be evaluated together.
How Marginal Cost and Marginal Revenue Work Together
The difference between marginal revenue and marginal cost is called marginal profit.
Marginal Profit = Marginal Revenue − Marginal Cost
Or:
MP = MR − MC
OpenStax describes marginal profit as the profit generated by one more unit of output, calculated as marginal revenue minus marginal cost.
The relationship produces three basic situations.
When Marginal Revenue Is Greater Than Marginal Cost
MR > MC
The additional unit generates more revenue than cost.
For example:
- MR = $60
- MC = $42
- Marginal profit = $18
Producing the unit adds $18 to total profit.
A profit-seeking company normally has an incentive to increase output while marginal revenue remains higher than marginal cost.
When Marginal Revenue Equals Marginal Cost
MR = MC
The additional unit adds the same amount to revenue and cost.
For example:
- MR = $50
- MC = $50
- Marginal profit = $0
This result helps explain What is the difference between marginal cost and marginal revenue? by showing how the relationship between the two determines the most profitable production level.
At this point, the additional unit does not increase total profit. Under standard conditions, this is the profit-maximizing output level because producing fewer units would leave profitable opportunities unused, while producing more would cause marginal cost to exceed marginal revenue.
When Marginal Cost Is Greater Than Marginal Revenue
MC > MR
The additional unit costs more to produce than it generates in revenue.
For example:
- MC = $58
- MR = $45
- Marginal profit = −$13
Producing the unit reduces total profit by $13.
The business may be producing too much and should evaluate whether output should be reduced.
Why Does MR = MC Maximize Profit?
The question “What is the difference between marginal cost and marginal revenue?” is central to understanding why the MR = MC rule identifies the profit-maximizing output.
Total profit equals total revenue minus total cost:
Profit = Total Revenue − Total Cost
The change in profit from producing another unit equals:
Change in Profit = Marginal Revenue − Marginal Cost
As long as MR is higher than MC, each additional unit increases profit.
Once MC becomes higher than MR, each additional unit decreases profit.
The highest total profit is therefore generally reached at the transition between those two conditions—the output at which marginal revenue equals marginal cost or the last practical unit before marginal cost exceeds marginal revenue.
MIT economics materials express the same logic mathematically: differentiating profit with respect to output produces marginal revenue minus marginal cost, so the interior first-order condition for profit maximization is MR = MC.
Why MR = MC Is Not Always Enough
Understanding “What is the difference between marginal cost and marginal revenue?” also helps explain why equality between MR and MC alone does not guarantee the highest possible profit.
The equation MR = MC identifies a possible profit-maximizing output, but equality alone does not prove that profit is at its highest point.
For the intersection to represent a maximum, marginal cost should generally cross marginal revenue from below:
- Immediately before the intersection, MR should be greater than MC.
- Immediately after the intersection, MC should be greater than MR.
This pattern means additional output first increases profit and then begins reducing it.
In calculus terms, the first derivative of profit is zero where MR equals MC. The second-order condition must also indicate that the profit function is concave at that point.
A company should therefore:
- Identify every feasible point where MR equals MC.
- Check whether profit changes from increasing to decreasing.
- Compare total profit at those points.
- Check practical boundary choices, including zero output and maximum capacity.
If output is restricted to whole units or production batches, MR may never equal MC exactly. The correct choice is then the feasible output level that produces the highest total profit.
Worked Example: Finding the Profit-Maximizing Output
Consider a small manufacturer evaluating five production levels.
| Quantity | Total Revenue | Total Cost | Total Profit |
| 100 | $5,000 | $3,200 | $1,800 |
| 110 | $5,480 | $3,540 | $1,940 |
| 120 | $5,920 | $3,920 | $2,000 |
| 130 | $6,300 | $4,380 | $1,920 |
| 140 | $6,600 | $4,940 | $1,660 |
Now calculate marginal revenue and marginal cost for each additional batch of 10 units.
| Production Increase | Change in Revenue | MR per Unit | Change in Cost | MC per Unit | Marginal Effect |
| 100 to 110 | $480 | $48 | $340 | $34 | Expand |
| 110 to 120 | $440 | $44 | $380 | $38 | Expand |
| 120 to 130 | $380 | $38 | $460 | $46 | Do not expand |
| 130 to 140 | $300 | $30 | $560 | $56 | Do not expand |
From 100 to 110 units:
MR = $480 ÷ 10 = $48
MC = $340 ÷ 10 = $34
Because MR exceeds MC, this expansion increases profit.
From 110 to 120 units:
MR = $440 ÷ 10 = $44
MC = $380 ÷ 10 = $38
The second expansion also increases profit.
From 120 to 130 units:
MR = $380 ÷ 10 = $38
MC = $460 ÷ 10 = $46
Marginal cost now exceeds marginal revenue. Producing this batch reduces total profit.
The best output among the available choices is therefore 120 units, where total profit reaches its highest value of $2,000.
The exact MR = MC point may fall somewhere between 120 and 130 units, but when production must occur in whole units or batches, the company should select the feasible quantity producing the highest profit.
Does MR = MC Mean the Business Is Breaking Even?
No.
Understanding what is the difference between marginal cost and marginal revenue? helps explain why the MR = MC point is not the same as the break-even point.
This is one of the most common misunderstandings about marginal cost and marginal revenue.
When MR equals MC, the marginal profit of the next unit is zero. It does not mean total company profit is zero.
A company can have MR = MC and still:
- Earn a substantial total profit
- Break even
- Operate at a loss
The result depends on total revenue compared with total cost, including relevant fixed and opportunity costs.
For example, suppose a company’s profit-maximizing output is 1,000 units and:
- Price per unit = $70
- Average total cost per unit = $50
- MR = MC at 1,000 units
Total profit is:
Profit = (Price − Average Total Cost) × Quantity
Profit = ($70 − $50) × 1,000
Profit = $20,000
The company earns $20,000 even though MR equals MC at its chosen output.
The MR = MC rule identifies the output that maximizes profit. Average cost and price determine whether the resulting maximum profit is positive, zero or negative. OpenStax similarly distinguishes the profit-maximizing condition from the break-even and shutdown conditions.
What Happens When MR Is Greater Than or Less Than MC?
1. Marginal Cost vs. Average Cost
Marginal cost and average cost answer different questions.
2. Average Cost
Average Cost = Total Cost ÷ Total Quantity
Average cost tells the company how much each unit costs on average across the entire production volume.
3. Marginal Cost
Marginal Cost = Change in Total Cost ÷ Change in Quantity
Marginal cost estimates how much the next unit or production increase costs.
Example
Suppose:
- Total cost of 1,000 units = $30,000
- Total cost of 1,001 units = $30,045
Average cost at 1,000 units is:
$30,000 ÷ 1,000 = $30
Marginal cost of the 1,001st unit is:
$30,045 − $30,000 = $45
The company’s average cost is $30, but the next unit costs $45.
Using average cost to make the expansion decision would understate the cost of producing the additional unit.
4. Marginal Revenue vs. Average Revenue
Average revenue is:
Average Revenue = Total Revenue ÷ Quantity Sold
When all units sell for the same price, average revenue equals price.
Marginal revenue measures the change in total revenue resulting from another unit or batch.
A business with pricing power can therefore have:
- Price = $50
- Average revenue = $50
- Marginal revenue = $30
The difference occurs because selling another unit may require reducing the price applied to existing sales.
5. Marginal Revenue vs. Total Revenue
Total revenue is the full amount earned from sales:
Total Revenue = Price × Quantity
Marginal revenue measures the change in total revenue.
Understanding what is the difference between marginal cost and marginal revenue? also requires recognizing how marginal revenue affects total revenue.
A company’s total revenue can continue rising even while marginal revenue declines. As long as marginal revenue remains positive, an additional sale still increases total revenue.
When marginal revenue reaches zero, total revenue is generally at its maximum with respect to quantity. When marginal revenue becomes negative, selling additional output reduces total revenue.
Maximum total revenue is not necessarily maximum profit because total cost must also be considered.
Marginal Revenue vs. Marginal Benefit
The question “What is the difference between marginal cost and marginal revenue?” becomes clearer when marginal revenue is also distinguished from marginal benefit.
Marginal revenue and marginal benefit both concern an additional unit, but they are measured from different perspectives.
Marginal revenue is the additional income a seller receives from selling one more unit.
Marginal benefit is the additional value or satisfaction received by a consumer—or, in policy analysis, the additional benefit received by society—from one more unit.
| Comparison | Marginal Revenue | Marginal Benefit |
|---|---|---|
| Perspective | Seller or producer | Consumer or society |
| Measures | Additional sales revenue | Additional value from consumption |
| Used for | Profit and output decisions | Consumer choice and efficiency analysis |
| Compared with | Marginal cost | Price or marginal social cost |
Marginal revenue may be lower than the buyer’s marginal benefit. For example, a customer may be willing to pay as much as $80 for a service, while the company earns only $50 in marginal revenue from the sale.
For a perfectly competitive market without significant external effects, price can serve as a measure of the marginal benefit received from the final unit. Allocative efficiency occurs where marginal benefit aligns with marginal cost. This is different from the individual company’s profit-maximization test, which compares marginal revenue with marginal cost.
Marginal Cost and Marginal Revenue Under Different Market Structures
Market structure affects the shape and behavior of marginal revenue.
Perfect Competition
A perfectly competitive firm:
- Accepts the market price
- Cannot individually influence price
- Faces constant marginal revenue equal to price
- Chooses output where P = MR = MC
OpenStax identifies P = MR = MC as the profit-maximizing condition for a perfectly competitive firm, provided the firm also satisfies the applicable short-run operating condition.
For a perfectly competitive firm, the upward-sloping portion of the marginal cost curve above the minimum average variable cost represents the firm’s short-run supply curve. At each market price, the company chooses the quantity where price equals marginal cost, provided the price is high enough to cover average variable cost.
When the market price falls below minimum average variable cost, the firm will generally minimize its short-run losses by temporarily shutting down rather than continuing production.
Monopoly
A monopolist:
- Faces the market demand curve
- Usually must lower price to sell more
- Has a downward-sloping marginal revenue curve
- Selects quantity where MR = MC
- Uses the demand curve to determine the price buyers will pay for that quantity
The monopolist does not normally set price equal to marginal cost. It first finds the quantity where MR equals MC and then identifies the corresponding price on the demand curve.
Monopolistic Competition
A monopolistically competitive business sells a differentiated product and faces a downward-sloping demand curve.
Examples may include restaurants, salons, local service providers and branded consumer products. Such a firm seeks the quantity where MR equals MC and then charges the price indicated by its perceived demand curve.
Oligopoly
In an oligopoly, a small number of significant competitors influence one another.
Marginal analysis remains useful, but estimating marginal revenue becomes more difficult because a price change, promotion or production increase may cause competitors to respond. Businesses may need to evaluate several demand and competitor-response scenarios rather than relying on a single MR curve.
Advanced Example Using Revenue and Cost Functions
Suppose a company faces the following inverse demand equation:
Price = 100 − Q
Where Q is quantity.
Total revenue is:
TR = Price × Quantity
TR = (100 − Q)Q
TR = 100Q − Q²
Marginal revenue is the derivative of total revenue:
MR = 100 − 2Q
Assume total cost is:
TC = 400 + 20Q
Marginal cost is:
MC = 20
To find the profit-maximizing quantity, set MR equal to MC:
100 − 2Q = 20
80 = 2Q
Q = 40
Now find the price using the demand equation:
Price = 100 − 40
Price = $60
At the profit-maximizing output:
- Quantity = 40
- Price = $60
- Marginal revenue = $20
- Marginal cost = $20
Notice that price is $60 while marginal revenue is $20. They are not equal because selling more output requires moving down the demand curve.
Total revenue is:
TR = $60 × 40 = $2,400
Total cost is:
TC = $400 + ($20 × 40)
TC = $1,200
Total profit is:
$2,400 − $1,200 = $1,200
This example also demonstrates why MR = MC does not mean total profit is zero.
How to Read an MR and MC Graph
A standard marginal analysis graph places:
- Quantity on the horizontal axis
- Cost and revenue per additional unit on the vertical axis
The marginal cost curve often falls initially and then rises as production approaches capacity limits.
The marginal revenue curve may be:
- Horizontal for a perfectly competitive firm
- Downward sloping for a firm with pricing power
The profit-maximizing output is normally where the rising MC curve intersects MR from below.
To the Left of the Intersection
MR is higher than MC.
Additional output adds more revenue than cost, so increasing production can raise profit.
At the Intersection
MR equals MC.
Marginal profit is approximately zero, and total profit is at or near its maximum.
To the Right of the Intersection
MC is higher than MR.
Additional output adds more cost than revenue, so reducing production can improve profit.
The Shutdown Rule: Why MR = MC Is Not the Only Test
Understanding what is the difference between marginal cost and marginal revenue? also requires recognizing that the MR = MC rule does not determine whether a business should continue operating when it is making a loss.
A perfectly competitive business may find an MR = MC output and still face a loss. The next question is whether the company should continue producing in the short run.
In the standard short-run model:
- If price covers average variable cost, the firm may continue operating even when it cannot cover total average cost.
- If price falls below average variable cost, the firm generally minimizes its short-run loss by shutting down.
OpenStax defines the shutdown point as the minimum of average variable cost and explains that a competitive firm should shut down when the market price falls below that level.
For real businesses, shutdown decisions may also depend on restart expenses, employee retention, contracts, customer relationships, safety obligations and long-term strategy.
How Businesses Use Marginal Cost and Marginal Revenue
What is the difference between marginal cost and marginal revenue? The answer becomes more practical when businesses apply both measures to production, pricing, staffing and expansion decisions.
Marginal analysis can support several practical decisions.
1. Production Planning
A manufacturer can compare the added revenue from another production run with the costs of labor, materials, machine time and shipping.
2. Special Orders
A business may receive a one-time order at a price below its normal selling price. The order may still add profit when:
- The price exceeds the relevant marginal cost.
- Existing sales are not displaced.
- The company has unused capacity.
- The order does not damage regular pricing.
- All additional fulfillment costs are included.
3. Pricing Decisions
A company can estimate how a discount affects both quantity sold and total revenue. This is especially important when the lower price applies to existing customers as well as new buyers.
4. Staffing
A restaurant, consultancy or service company can compare the revenue made possible by an additional employee with the incremental wages, payroll costs, training and supervision required.
5. Capacity Expansion
A company considering another machine, location or warehouse should compare the incremental revenue generated by the expansion with all incremental operating and capital costs.
6. Digital Products
Software and digital products may have a low direct cost for an additional user, but marginal cost is not always zero. Additional usage can create costs involving:
- Cloud infrastructure
- Payment processing
- Customer support
- Fraud prevention
- Data storage
- Content licensing
- Onboarding
- Regulatory compliance
7. Marketing Campaigns
Businesses can compare marginal customer revenue with the marginal cost of acquiring and serving an additional customer.
The analysis should use contribution after refunds, payment fees, fulfillment, support and other incremental expenses—not merely gross sales.
How to Calculate Marginal Cost and Marginal Revenue From Business Data
Step 1: Define the Decision
Specify the exact change being considered.
Examples include:
- Producing 100 additional units
- Adding a weekend shift
- Accepting a custom order
- Reducing price by 5%
- Adding 500 subscribers
- Opening another delivery area
Step 2: Select a Relevant Time Period
Revenue and cost data must cover the same period.
Do not compare monthly additional revenue with weekly additional cost.
Step 3: Estimate the Change in Quantity
Identify the difference between the current and proposed output or sales level.
Step 4: Estimate Total Revenue at Both Levels
Include expected changes in:
- Selling price
- Discounts
- Returns
- Product mix
- Lost sales of existing products
- Customer cancellations
- Competitor reactions
Step 5: Estimate Total Cost at Both Levels
Include every cost that changes because of the decision.
Consider:
- Materials
- Labor
- Overtime
- Packaging
- Freight
- Commissions
- Support
- Processing fees
- Maintenance
- Waste
- Capacity expansion
Step 6: Calculate MR and MC
- MR = Change in Total Revenue ÷ Change in Quantity
- MC = Change in Total Cost ÷ Change in Quantity
Step 7: Compare the Results
- MR > MC: Expansion may increase profit.
- MR = MC: Output may be near the profit-maximizing point.
- MR < MC: Expansion may reduce profit.
Step 8: Test Alternative Scenarios
Because demand and costs are estimates, calculate:
- Best-case scenario
- Expected scenario
- Worst-case scenario
A decision that is profitable only under an optimistic forecast may carry significant risk.
Common Mistakes When Comparing Marginal Cost and Marginal Revenue
Understanding what is the difference between marginal cost and marginal revenue? can help businesses avoid common errors when evaluating production, pricing and profitability decisions.
1. Using Average Cost Instead of Marginal Cost
Average cost summarizes all units. It may not reflect overtime, congestion or capacity expenses affecting the next unit.
2. Assuming Marginal Revenue Always Equals Price
This is generally true for a competitive price-taking firm, but not for a company that must reduce prices to sell more output.
3. Ignoring the Effect of Discounts on Existing Sales
A price reduction can lower revenue from units the business would have sold anyway.
4. Allocating Unchanged Fixed Costs to the Decision
A cost should not be treated as marginal unless it changes because of the proposed output increase.
5. Ignoring Step Costs
An expansion may require another machine, manager, vehicle, license or warehouse. Such costs can create a sudden jump in marginal cost.
6. Treating MR = MC as the Break-Even Point
MR = MC concerns the profitability of the next unit. Break-even concerns total revenue compared with total cost.
7. Focusing Only on Revenue
An expansion that increases total revenue can still reduce profit when its additional cost is larger than its additional revenue.
8. Ignoring Opportunity Cost
Using limited capacity for one product may prevent the company from producing a more profitable product.
9. Assuming Estimates Are Certain
Demand, returns, material prices and competitor behavior can change. Marginal analysis should include sensitivity testing.
9. Continuing Production After MC Exceeds MR
More sales are not always better. Beyond the optimal quantity, additional output can lower total profit.
Limitations of Marginal Analysis
Understanding what is the difference between marginal cost and marginal revenue? also requires recognizing that both figures depend on estimates that may change over time.
Marginal cost and marginal revenue are useful, but the quality of the decision depends on the quality of the estimates.
Potential limitations include the following:
- Demand may be difficult to forecast.
- Costs may change unexpectedly.
- Competitors may react to price changes.
- Output may be available only in large batches.
- Product quality may decline when capacity is stretched.
- Current expansion may affect future customer expectations.
- Environmental or social costs may not appear in company accounting records.
- Long-term investments may create benefits that are not visible in short-term MR.
- Multiple products may share capacity and overhead.
- Legal, safety or contractual obligations may limit production choices.
Managers should combine marginal analysis with cash-flow forecasting, capacity planning, risk assessment and long-term strategy.
Marginal Cost vs. Marginal Revenue Decision Checklist
For businesses comparing marginal cost and marginal revenue, the following checklist can support a more accurate production decision.
Before increasing output, ask:
- How much additional revenue will the change generate?
- Will the selling price need to decrease?
- Will that decrease affect existing sales?
- Which expenses will genuinely increase?
- Will the expansion trigger overtime or step costs?
- Is production capacity available?
- Could the new product displace a more profitable product?
- Are refunds, returns and support expenses included?
- How sensitive is the result to lower-than-expected demand?
- Is MR greater than MC after considering all relevant effects?
- Does the decision support the company’s long-term strategy?
- Are there legal, safety or operational constraints?
Conclusion
Understanding what is the difference between marginal cost and marginal revenue? helps businesses make smarter production, pricing and expansion decisions.
Marginal cost measures the additional expense of producing more output. Marginal revenue measures the additional income earned from selling that output. The difference between them reveals whether the next unit adds to profit.
When MR is greater than MC, increasing production can improve profit. When MC is greater than MR, additional production can reduce profit. Under standard economic conditions, the most profitable output is found where marginal revenue equals marginal cost or at the last feasible unit before marginal cost moves above marginal revenue.
The strongest analysis does not rely on averages or sales growth alone. It measures the real incremental revenue and every relevant incremental cost associated with the next business decision.
Ultimately, answering what is the difference between marginal cost and marginal revenue? allows decision-makers to compare the income and expense created by additional output before committing resources.
What Is the Difference Between Marginal Cost and Marginal Revenue FAQs
1. What Is the Difference Between Marginal Cost and Marginal Revenue When Capacity Is Limited?
Capacity limits can increase marginal cost and reduce the revenue gained from extra output.
2. What Is the Difference Between Marginal Cost and Marginal Revenue If MR Never Equals MC?
Compare total profit at each feasible output level and choose the most profitable option.
3. What Is the Difference Between Marginal Cost and Marginal Revenue in Service Businesses?
Marginal cost covers serving one more customer, while marginal revenue is the income from that customer.
4. What Is the Difference Between Marginal Cost and Marginal Revenue After Taxes?
Per-unit taxes may increase marginal cost, while demand-related taxes may reduce marginal revenue.
5. What Is the Difference Between Marginal Cost and Marginal Revenue During Seasonal Demand?
Seasonal demand can change selling prices, sales volume and the profitability of additional output.
Disclaimer
This article is for educational purposes only and does not constitute financial, accounting or business advice. Actual costs, revenue and profit decisions may vary by company and market conditions.
