How to calculate contribution margin
Contribution margin is how much each sale contributes toward covering your fixed costs — and, once those are covered, toward profit. It's the number underneath break-even and smart pricing.
Skip the math — the free break even calculator runs this from your own figures.
Open the free calculator →The formula
Contribution margin per unit is your selling price minus the variable cost of that unit — the costs that only exist because you made the sale, like materials, shipping, and payment fees.
Sell something for $60 with $25 of variable cost and each sale contributes $35. As a ratio, that's $35 ÷ $60, or about 58% — the share of each dollar of revenue that's left to cover fixed costs.
Variable vs fixed costs
The whole calculation depends on splitting your costs correctly. Variable costs rise and fall with each sale. Fixed costs — rent, salaries, software — stay roughly the same whether you sell ten units or ten thousand.
Only variable costs come out of the contribution margin. Fixed costs are what the margin is there to cover.
Why it drives break-even
Once you know the contribution per sale, break-even is simple: divide your fixed costs by the contribution margin per unit, and you have the number of sales you need just to cover everything.
This is why raising price or cutting variable cost is so powerful — both lift the contribution margin, which lowers the sales you need to break even and speeds up profit.
Using it to make decisions
Contribution margin tells you which products are actually pulling their weight. A high-revenue product with a thin margin can contribute less than a cheaper one with a fat margin — so it guides what to promote and what to reprice.
The free break-even calculator below computes your contribution margin and break-even point together, from your own numbers.
Questions
What's the difference between contribution margin and gross margin?
They're close but not identical. Gross margin subtracts the cost of goods sold; contribution margin subtracts all variable costs, which can include some selling costs beyond production. Contribution margin is the more precise tool for break-even and pricing decisions.
Can contribution margin be negative?
Yes — if your variable cost per sale is higher than your price, every sale loses money before fixed costs even enter the picture. That's a signal to raise price or cut variable cost immediately.