finedu
The path · Stage 5: Diagnosis and value
Unit 18 of 24

What makes growth profitable?

Contribution, break-even, operating leverage, and what a customer is really worth.

The ScorecardStock or flow?
Lesson 1 of 3 3 min read, then a check

Contribution pays the fixed bill

Fenwick Prints sells framed posters for $50. The frame, paper and ink cost $30 a print. Rent and the studio's one employee cost $4,000 a month whether it sells one print or a thousand. The owner wants one number: how many prints pay the bills.

Contribution is what a sale leaves after its own variable costs. Unit contribution = price − variable cost = 50 − 30 = $20. Which costs count as variable is a stated definition, not a law of nature; say which ones you used. Contribution pays the fixed costs first, and only the remainder is profit.

Break-even is fixed costs divided by unit contribution. 4,000 ÷ 20 = 200 prints a month, provided contribution is positive. At 250 prints, profit = 250 × 20 − 4,000 = $1,000. If break-even lands on a fraction, round up: 205.5 prints means 206, because 205 still loses money.

Contribution crosses fixed costs at 200 prints

This is a Scorecard (income statement) question with a stock-or-flow twist. Fixed costs are a flow per period, so break-even is a volume per period. Two hundred prints means 200 a month, every month, not 200 and done.

Try it

The break-even frontier

Operating profit1,000
5100
0100
010000
01000
Break-even = 4000 ÷ (50 − 30) = 200 units (200 whole units)
Read the mechanism

Each unit's contribution pays the fixed bill first and only then creates profit. If the variable cost climbs above the price, every extra sale digs the hole deeper. The straight line holds only while prices, costs and capacity stay put.

Model assumptions and units

One product, a constant price and unit cost, and fixed costs that stay fixed across the modeled range. Capacity limits, step costs and mix changes are left out. Round a fractional break-even up when only whole units can be sold.

When variable cost exceeds price, volume makes the loss bigger. At $60 of variable cost, each print loses $10 before rent, so 250 prints lose 250 × 10 + 4,000 = $6,500 and 500 prints lose $9,000. There is no volume that breaks even, because the fixed cost never gets covered. Only price, cost, mix or the model itself can fix negative contribution.

Fixed means fixed within a range and a period. A second employee, a bigger studio or a new press is a step, and each step moves the line. A straight line drawn past the studio's capacity is a drawing, not a plan.

Margin of safety is how far sales can fall before break-even. At 250 prints against a break-even of 200, it is 50 prints, or 50 ÷ 250 = 20%. Operating leverage is how sharply profit reacts when fixed costs are large. Sell 275 prints instead of 250, a 10% rise, and profit goes from $1,000 to 275 × 20 − 4,000 = $1,500, a 50% rise. That is arithmetic near break-even, not evidence that demand is volatile.

Quick check

Fenwick's fixed costs rise to $9,000 a month. It lifts the price to $80 and variable cost is now $50. Break-even?

Explain it back40 more characters to count

Why is "we will make it up in volume" wrong when each incremental unit loses money before fixed costs?

Sources and further reading

MIT OpenCourseWare · Introduction to Financial and Managerial Accounting

Original explanations and fictional examples. Sources reviewed September 2026. See the method and scope.