Contribution Margin
$$\text{CM} = \text{Revenue} - \text{Variable Costs}$$
What is Contribution Margin?
Contribution Margin (CM) is the revenue remaining after all variable costs are deducted. It represents the amount each unit sold contributes toward covering fixed costs and, once fixed costs are fully covered, to operating profit. It is calculated at the total level (CM = Revenue − Variable Costs) or at the per-unit level (CM per unit = Price − Variable Cost per Unit).
Contribution Margin Ratio (CM Ratio) expresses CM as a percentage of revenue, showing how many cents out of every revenue dollar are available to cover fixed costs and profit. A 60% CM Ratio means for every $100 in sales, $60 is available for fixed costs and profit — the other $40 is consumed by variable costs.
CM differs from Gross Profit in an important way: COGS typically includes some fixed manufacturing overhead, while CM's variable cost definition includes only truly variable expenses. For decision-making — whether to accept a specific order, which product to prioritise, what happens if volume changes — CM is more decision-relevant than gross profit.
When to use Contribution Margin
Use Contribution Margin for product mix decisions (which products to prioritise with limited capacity), pricing analysis (is a discounted order still worth accepting?), break-even calculations, and evaluating the profit impact of volume changes. The rule: accept any incremental order priced above variable cost — it contributes something toward fixed costs even if it is below full cost.
Worked examples
| Product | Price | Variable Cost | CM / Unit | CM Ratio | Fixed Allocation | Full-Cost Profit |
|---|---|---|---|---|---|---|
| Product A | $80 | $32 | $48 | 60% | $30 | $18 |
| Product B | $50 | $35 | $15 | 30% | $20 | −$5 |
| Product C | $120 | $50 | $70 | 58% | $60 | $10 |
Common pitfalls
Focusing solely on CM can lead to decisions that look good in the short term but are strategically harmful. Product B in the example above has negative full-cost profit but positive CM — so it contributes toward fixed costs in the short run. But relying on low-CM products long-term prevents the business from covering its fixed cost base. Always evaluate CM in context of the overall product mix and strategic capacity constraints.
Frequently asked questions
What is the difference between contribution margin and gross profit?
Gross Profit = Revenue − COGS, where COGS typically includes both variable costs (materials, direct labour) and fixed manufacturing overhead (factory rent, production staff salaries). Contribution Margin = Revenue − Variable Costs only. For a manufacturer with $500,000 in fixed factory overhead spread across 100,000 units, each unit carries $5 of fixed cost in COGS but nothing in its variable cost. In that case, CM per unit will be $5 higher than gross profit per unit.
How does contribution margin relate to break-even?
Break-even is directly derived from CM: Break-Even Units = Fixed Costs ÷ CM per Unit. Increasing CM (by raising prices or cutting variable costs) directly reduces the break-even volume. This makes CM improvement one of the most powerful levers for business model health.
What is a good contribution margin ratio?
It varies significantly by industry. SaaS and software companies typically have CM Ratios of 60–80% because variable costs (hosting, payment processing) are very low. Service businesses range from 30–60%. Manufacturing 30–50%. Retail and distribution 20–40%. There is no universal benchmark — compare against industry peers and evaluate trend over time.