Quick answer
Marginal revenue = change in total revenue ÷ change in quantity. Selling 20 more units (100 to 120) lifted revenue from $2,000 to $2,400, so marginal revenue is $400 ÷ 20 = $20.00.
Enter total revenue and quantity before and after. The calculator returns the revenue from each extra unit.
Related tools: Marginal Cost Calculator: Extra cost of producing additional units. Revenue Calculator: Revenue from price and units sold. Price Elasticity of Demand Calculator: Price elasticity of demand by the midpoint (arc) method.
How to use the Marginal Revenue Calculator
- Enter total revenue before ($) (0 or more).
- Enter total revenue after ($) (0 or more).
- Enter quantity before (0 or more).
- Enter quantity after (0 or more).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Total revenue before | A number, in $ | ≥ 0 |
| Total revenue after | A number, in $ | ≥ 0 |
| Quantity before | A number | ≥ 0 |
| Quantity after | A number | ≥ 0 |
Formula and method
Formula
marginal revenue = ΔR ÷ ΔQ
IEEE-754 double precision; shown to the decimals indicated.
Revenue per additional unit between two sales levels.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Total revenue before = 2000; Total revenue after = 2400; Quantity before = 100; Quantity after = 120.
| Result | Value |
|---|---|
| Marginal revenue | $20.00 |
Example 2
Inputs: Total revenue before = 900; Total revenue after = 1000; Quantity before = 30; Quantity after = 40.
| Result | Value |
|---|---|
| Marginal revenue | $10.00 |
The first line is the headline result (marginal revenue). IEEE-754 double precision; shown to the decimals indicated.
Compare it with marginal cost
A firm maximises profit where marginal revenue equals marginal cost. If marginal revenue ($20) exceeds marginal cost, producing more adds profit. Under a falling price, marginal revenue is below the price because lowering the price applies to every unit.
Reading the example
The average price before was $20 and after is $20, so marginal revenue equals the price here; this indicates a price-taker. When marginal revenue is lower than price, the firm is cutting prices to sell more.
How the result changes with total revenue before
Holding every other input at the first worked example, this table changes only total revenue before. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Total revenue before | Marginal revenue |
|---|---|
| 1000 | $70.00 |
| 2000 | $20.00 |
| 4000 | -$80.00 |
| 8000 | -$280.00 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Quantity after: entering "5" shows "The quantities must be different." beside that field and no result.
- Total revenue before: left empty shows "Enter total revenue before." beside that field and no result.
Choosing between the Marginal Revenue Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Marginal Cost Calculator](/business/marginal-cost/) | total cost before, total cost after and quantity before | Marginal cost |
| [Revenue Calculator](/business/revenue/) | price per unit and units sold | Revenue |
| [Price Elasticity of Demand Calculator](/business/price-elasticity-demand/) | price before, price after and quantity before | Price Elasticity of Demand |
| [GDP Calculator](/business/gdp-calculator/) | consumption, investment and government spending | GDP |
| [Opportunity Cost Calculator](/business/opportunity-cost/) | return of the option you gave up and return of the option you chose | Opportunity cost |
Background: business metrics
Business ratios depend on exactly which costs and revenues you include, so read each page's definition. Two common checks: break-even units = fixed costs ÷ (price − variable cost per unit), so $50,000 of fixed costs with a $10 price and $5 variable cost breaks even at 10,000 units; and net profit margin = net profit ÷ revenue, so $20,000 profit on $100,000 revenue is 20%.
Return on investment ignores time: 20% over five years is far less impressive than 20% in one, so compare returns over the same period.
Assumptions and limitations
- Quantities must differ
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for quantity after and total revenue before to confirm this.
Frequently asked questions
Can marginal revenue be negative?
Yes, if selling more requires price cuts big enough to reduce total revenue.
How is it different from price?
Price is revenue per unit; marginal revenue is the added revenue from one more unit.
Do the quantities need to differ?
Yes, otherwise the change in quantity is zero.
What does the Marginal Revenue Calculator calculate?
Extra revenue from selling additional units. It returns Marginal revenue.
What formula does the Marginal Revenue Calculator use?
marginal revenue = ΔR ÷ ΔQ. Revenue per additional unit between two sales levels.
What do I need to enter in the marginal Revenue Calculator?
You enter Total revenue before ($), Total revenue after ($), Quantity before and Quantity after.
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Quantities must differ.
What is an example of a marginal Revenue result?
With total revenue before 2000, total revenue after 2400, quantity before 100 and quantity after 120, the marginal revenue is $20.00.
Related calculators
- Marginal Cost Calculator — Extra cost of producing additional units.
- Revenue Calculator — Revenue from price and units sold.
- Price Elasticity of Demand Calculator — Price elasticity of demand by the midpoint (arc) method.
- GDP Calculator — Gross domestic product by the expenditure approach.
- Opportunity Cost Calculator — Value given up by choosing one option over another.
- Income Elasticity of Demand Calculator — Income elasticity of demand by the midpoint (arc) method.
Sources
- OpenStax, Principles of Accounting, Volume 2: Managerial Accounting (Rice University)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.