Contribution margin and break-even: how many sales cover the costs
Every sale of a product adds something toward paying the fixed costs, and once those are paid, the rest is profit. That amount is the contribution margin, and it leads straight to the break-even point, the target-profit volume and the margin of safety. This lesson works all four on a fictional bicycle maker, then extends the lesson-one cost lines for Apple and Microsoft to show what the method gives when pushed too far.
- Level
- Beginner
- Reading time
- About 22 minutes
- Know this first
- Fixed, variable and mixed costs
By the end you will be able to:
- calculate contribution margin per unit and as a ratio
- find break-even in units and in sales dollars, and the volume needed for a target profit
- calculate the margin of safety and say what it measures
- list the assumptions behind break-even analysis and say when they stop holding
The question every owner asks first
Before a business can make a profit it has to cover its fixed costs, and the first question anyone asks about a new product, shop or factory is how much must be sold before that happens. Cost-volume-profit analysis answers it with a few lines of arithmetic, built on the split between fixed and variable costs from the previous lesson. It gives the break-even point, the volume needed for a chosen profit, and a measure of how far sales could fall before a loss begins.
The running example is still the fictional bicycle maker, invented for these lessons. It now has a selling price of $200 a bicycle, variable costs of $125 a bicycle, and fixed costs of $240,000 a year. Apple and Microsoft come in near the end, to show what happens when the same method is pushed beyond the range it was made for.
Contribution margin: what each sale adds
The contribution margin is the selling price less the variable costs of the sale. It is what is left from each sale to contribute toward fixed costs, and then toward profit. Each bicycle sells for $200 and has variable costs of $125, so it contributes $75.00. Divided by the price, that is the contribution margin ratio: 37.5% of every sales dollar is left after variable costs, and the other part is spent on them.
The word margin is also used for gross margin, which is sales less the whole cost of goods sold, fixed manufacturing overhead included. Contribution margin is a different measure. It subtracts only the costs that rise and fall with each sale, which is why it is the one that matters when the question is what a change in volume does to profit.
The break-even point
The business breaks even when total contribution exactly equals fixed costs, so profit is zero. Dividing the fixed costs by the contribution of each unit gives the number of units, and dividing by the ratio gives the same point in sales dollars.
For the bicycle maker, $240,000 ÷ $75.00 = 3,200 bicycles, and $240,000 ÷ 37.5% = $640,000 of sales, which is 3,200 × $200. When the division does not come out in whole units, the answer is rounded up, because a fraction of a bicycle cannot be sold and the last one is needed to cover the cost. The table shows profit at five volumes, laid out so that contribution can be seen covering fixed costs first and then turning into profit.
| Bicycles sold | Sales | Variable costs | Contribution | Fixed costs | Profit or loss |
|---|---|---|---|---|---|
| 2,000 | $400,000 | $250,000 | $150,000 | $240,000 | −$90,000 |
| 3,200 | $640,000 | $400,000 | $240,000 | $240,000 | $0 |
| 5,000 | $1,000,000 | $625,000 | $375,000 | $240,000 | $135,000 |
| 8,000 | $1,600,000 | $1,000,000 | $600,000 | $240,000 | $360,000 |
| 12,000 | $2,400,000 | $1,500,000 | $900,000 | $240,000 | $660,000 |
At the break-even volume the contribution equals the fixed costs exactly and profit is nil. Below it every bicycle reduces the loss by $75, and above it every bicycle adds $75 to profit. Profit does not grow in a jump at the break-even point. It changes by the same $75 with each sale throughout. That straight line is an assumption, and one worth doubting when the method is used on a real business whose costs do not behave so neatly.
Move price, costs and volume
Change any of five inputs. The left page shows the contribution margin and the break-even point. The right page shows profit at the chosen volume, the margin of safety, and the volume needed to reach a profit goal.
Each bicycle sells for $200.00 and costs $125.00 to make and sell, so it adds $75.00 (37.5% of the price) toward the $240,000 of fixed costs. The business breaks even at 3,200 bicycles, or $640,000 of sales. At 8,000 bicycles the profit is $360,000, and sales could fall 60.0% before it reached break-even. To earn $150,000 it needs 5,200 bicycles.
Four experiments. First, the starting settings give a contribution of $75.00, break-even at 3,200 bicycles and a profit of $360,000 at 8,000. Second, cut the price to $180: the contribution falls to $55, break-even rises to 4,364 bicycles and profit falls to $200,000. A drop of a tenth in the price removed more than two-fifths of the profit, which is the effect of price falling straight through to contribution. Third, move the volume to 2,000 and the figure for the margin of safety turns negative, showing the shortfall from break-even, while profit becomes a loss. Fourth, set the price to $100 so that it is below the $125 variable cost: each sale now loses money, no volume can break even, and the calculator says so. Selling more of something that loses money on every sale makes the loss larger.
Profit goals and the margin of safety
A profit goal is treated as one more cost to be covered. Add it to the fixed costs and divide by the contribution per unit.
A profit of $150,000 needs ($240,000 + $150,000) ÷ $75.00 = 5,200 bicycles, or $1,040,000 of sales. If the goal is a profit after tax, divide it by one less the tax rate to get the profit before tax, and use that in the formula. A goal of $60,000 after a 25% tax rate is $80,000 before tax.
The margin of safety is the amount by which sales exceed break-even, usually shown as a share of expected sales. At 8,000 bicycles the break-even point is 3,200, so sales could fall by 60% before profit disappeared. A business with a margin of safety of 60% can take a bad year; one with a margin of 5% cannot. Two businesses with the same profit can have very different margins of safety, depending on how much of their costs are fixed. The next lesson takes that thought further.
Which change hurts the most?
Break-even analysis is used for what-if questions. The table changes one input by ten percent at a time and holds the others at their starting values.
| One change at a time, 8,000 bicycles | Contribution per bicycle | Break-even bicycles | Profit | Margin of safety |
|---|---|---|---|---|
| Starting position | $75.00 | 3,200 | $360,000 | 60.0% |
| Price 10% lower ($180) | $55.00 | 4,364 | $200,000 | 45.5% |
| Variable cost 10% higher ($137.50) | $62.50 | 3,840 | $260,000 | 52.0% |
| Fixed costs 10% higher ($264,000) | $75.00 | 3,520 | $336,000 | 56.0% |
| Volume 10% lower (7,200) | $75.00 | 3,200 | $300,000 | 55.6% |
The price cut is far more damaging than the others. A ten percent cut in price takes $20 off each sale and every dollar of it comes out of contribution, while a ten percent rise in the variable cost takes $12.50 off and a ten percent rise in fixed costs takes $24,000 off the year in total. A fall of ten percent in volume leaves the break-even point where it was, and lowers profit by the lost contribution on 800 bicycles. The cost structure decides which inputs matter most, and the calculator will show it for any other set of numbers.
What happens on Apple and Microsoft
The previous lesson drew a line through each company's total costs for fiscal 2024 and 2025, and found that each extra dollar of revenue came with about 60.9 cents of extra cost at Apple and 47.8 cents at Microsoft. One less that rate is a contribution margin ratio, and with the fixed part implied by the line, a break-even point follows. It is a mechanical exercise, done here to show how far the method can be trusted.
| Break-even implied by the two-point lines, $ billion | Apple | Microsoft |
|---|---|---|
| Revenue, fiscal 2025 | 416.2 | 281.7 |
| Contribution margin ratio (one less the cost rate) | 39.1% | 52.2% |
| Implied fixed part of costs | 29.8 | 18.4 |
| Implied break-even revenue | 76.2 | 35.4 |
| Implied margin of safety | 81.7% | 87.4% |
The line puts Apple's break-even revenue at $76.2 billion and Microsoft's at $35.4 billion, against fiscal 2025 revenue of $416.2 billion and $281.7 billion. The implied margins of safety are 81.7% and 87.4%.
These are not margins of safety that either company has. The line was fitted through two years of results, with revenue between $390 billion and $420 billion at Apple, and the break-even it gives lies at less than a fifth of that. Nothing in the data says what costs would do at that scale. Costs that look fixed on the line, such as research spending, are set by management and would be changed long before sales fell that far, so the "fixed" part is fixed only within the narrow range the two points came from. The calculation is the relevant-range warning from the previous lesson in practice: a straight line is reliable near the data it came from and increasingly unreliable far from it. Use a break-even point only for volumes close to the range where the costs have been observed.
Assumptions and limits
The method is simple because it assumes a good deal. Each of these should be true, or nearly true, within the range being studied:
- Costs are linear. Variable cost per unit is constant and fixed costs do not change within the range. Discounts, overtime and the need for a second factory all break this.
- The selling price is constant. Selling more often requires lowering the price, which changes the contribution.
- Everything produced is sold. The calculation ignores changes in inventory, so it fits a business that sells what it makes.
- The sales mix is constant. With several products, a different mix changes the average contribution margin and moves the break-even point.
- The classification is right. A cost wrongly called fixed or variable shifts the result directly.
- It is a profit measure, not a cash measure. Break-even covers accounting costs, including depreciation. A business can reach it and still run short of cash.
Common mistakes
Dividing fixed costs by the price
Fixed costs are covered by the contribution, which is the price less variable costs. Using the whole price understates the break-even point badly: $240,000 ÷ $200 is 1,200 bicycles, not 3,200.
Mixing units and dollars
Dividing by the contribution per unit gives a number of units; dividing by the ratio gives sales dollars. Pairing the wrong denominator with the wrong answer is the most common arithmetic slip.
Forgetting that a profit goal is after tax
If the goal is a profit after tax, convert it to profit before tax first. Adding the after-tax figure directly to fixed costs underestimates the volume.
Treating the break-even point as a forecast
It says what volume is needed. It does not say that volume will be reached. The margin of safety is the better guide to risk.
Reading the line beyond the data
As the Apple and Microsoft figures show, the answer is only as good as the range the costs came from.
Try it yourself
1. A product sells for $50 and has a variable cost of $30. Fixed costs are $100,000 a year. What is the break-even point in units and in sales?
Show the working
Contribution = 50 − 30 = $20 per unit. Break-even units = 100,000 ÷ 20 = 5,000. Break-even sales = 5,000 × $50 = $250,000. Check with the ratio: 20 ÷ 50 = 40%, and 100,000 ÷ 0.40 = $250,000.
2. For the same product, how many units must be sold to earn a profit of $40,000?
Show the working
Units = (100,000 + 40,000) ÷ 20 = 7,000. That is 2,000 units beyond break-even, and 2,000 × $20 = $40,000 of profit.
3. If the product sells 8,000 units, what is the margin of safety?
Show the working
Sales exceed break-even by 8,000 − 5,000 = 3,000 units. As a share of expected sales that is 3,000 ÷ 8,000 = 37.5%. Sales could fall by that much before the product made a loss.
4. A business has a contribution margin ratio of 40% and fixed costs of $120,000. What sales does it need to break even?
Show the working
Break-even sales = 120,000 ÷ 0.40 = $300,000. At that level, contribution is 40% of $300,000 = $120,000, which equals the fixed costs.
5. The first product needs to earn $60,000 after tax at a tax rate of 25%. How many units must it sell?
Show the working
Profit before tax = 60,000 ÷ (1 − 0.25) = $80,000. Units = (100,000 + 80,000) ÷ 20 = 9,000.
Where this is used
- A founder checks whether a plan for a new product can reach break-even within a realistic share of the market.
- A retailer weighing a new shop compares the sales needed to cover its rent and staff with what comparable shops achieve.
- A manager testing a price rise or a promotion estimates how much volume could be lost before profit is worse off.
- A lender asks for the margin of safety in a borrower's plan, to judge how far sales could miss before the loan is at risk.
Key terms
- Cost-volume-profit analysis
- The study of how costs, volume and prices together determine profit.
- Contribution margin
- Selling price less variable cost, for a unit or in total: what a sale adds toward fixed costs and profit.
- Contribution margin ratio
- Contribution margin as a share of sales.
- Break-even point
- The volume, or the sales, at which total contribution equals fixed costs and profit is nil.
- Profit goal
- A chosen profit, treated as an extra amount to be covered by contribution.
- Margin of safety
- The amount by which expected sales exceed break-even sales, often as a share of expected sales.
- Sales mix
- The proportions in which a business sells its different products.
Questions people ask
Is contribution margin the same as gross margin?
No. Gross margin is sales less the whole cost of goods sold, which includes fixed manufacturing overhead. Contribution margin subtracts only variable costs, including variable selling costs such as commission.
Can a business break even and still fail?
Yes. Break-even is about accounting profit. A business can cover its costs on paper and still run out of cash if customers pay late or inventory builds up, as the earlier cash-flow lessons showed.
What if a business sells several products?
Use the average contribution margin ratio for the mix. The result holds only while the mix stays the same, so a shift to lower-margin products raises the break-even point even if total sales are unchanged.
Why is the fictional example used again?
Real companies do not publish their cost behaviour, so the mechanics are shown where every number is known, and the real statements show how far the method can be taken.
Sources and review
- Apple Inc., Form 8-K, Exhibit 99.1: fourth quarter and full-year fiscal 2025 results, filed with the US Securities and Exchange Commission. Source of Apple's statements.
- Microsoft Corporation, Form 8-K, Exhibit 99.1: fourth quarter and fiscal year 2025 results, filed with the US Securities and Exchange Commission. Source of Microsoft's statements.
- OpenStax, Principles of Accounting, Volume 2: Managerial Accounting, section 3.2: Calculate a break-even point in units and dollars, for the break-even, profit-goal and after-tax formulas.
- OpenStax, Principles of Accounting, Volume 2: Managerial Accounting, chapter 3 summary, for the margin of safety and the assumptions of cost-volume-profit analysis.
How the numbers were checked: the contribution margin, break-even, profit goal and margin of safety were recomputed in plain code at the starting settings and in the what-if cases, the profit table was checked two ways (statement layout and contribution layout), and the calculator, which runs separately, was compared with that code across a grid of inputs. The break-even points for Apple and Microsoft were rebuilt from the filed income statements.