Contribution Margin

Contribution margin answers a specific question: for every dollar of revenue, how much is left after covering the costs that vary directly with that sale? What remains contributes to covering fixed costs — and once fixed costs are covered, to profit.

Contribution margin vs. gross profit

These are similar concepts but with a meaningful difference. Gross profit uses COGS, which can include some fixed costs (like a salaried production employee). Contribution margin uses only variable costs — those that change with each unit sold or each job completed. In practice, for many service businesses, contribution margin and gross profit are nearly the same. For businesses with mixed direct labor (some fixed, some variable), they diverge.

Why it matters for pricing decisions

Contribution margin is the right lens for pricing analysis. If you're deciding whether to take on a job at a discounted rate, the question isn't whether the job covers all your overhead — it's whether the job's contribution margin is positive. Any positive contribution covers some fixed costs you'd have regardless. Contribution margin thinking prevents the mistake of turning down work that would have helped — even if it doesn't fully cover overhead.

Contribution margin per unit

If you sell a product for $80 and the variable cost per unit is $30, the contribution margin per unit is $50. If your fixed costs are $25,000/month, you need to sell 500 units per month to break even. This is how break-even analysis works in practice — dividing fixed costs by the per-unit contribution margin.