Definition (canonical)
Contribution margin is what's left from revenue after subtracting variable costs — the money each sale "contributes" toward covering fixed costs and then profit: contribution margin = revenue − variable costs. It can be shown per unit or as a ratio of revenue. Unlike gross margin, it hinges on the fixed-versus-variable split, which makes it the core tool for pricing, break-even and product-mix decisions.
Why it matters
Every sale first has to pay back its own variable cost; whatever remains is the contribution that chips away at fixed costs. Once cumulative contribution equals fixed costs, you hit break-even — and every sale after that is profit. This is why contribution margin, not gross margin, answers questions like "should I take this discounted order?" or "which product funds the business fastest?" A product with lower revenue but higher contribution margin can be worth more than a bigger, thinner one. It is the backbone of sound unit economics.
Contribution margin vs gross margin
They look similar but split costs differently. Gross margin subtracts cost of goods sold (which mixes some fixed production costs); contribution margin subtracts only truly variable costs (materials, shipping, payment fees, sales commissions). So a factory's depreciation sits inside COGS (reducing gross margin) but is excluded from contribution margin. For decisions at the margin — one more order, one more unit — contribution margin is the honest number, because fixed costs don't change with the next sale. See the general concept of margin for how these relate.
How to use it
Compute contribution margin per unit to set a price floor: never accept a price below variable cost, or each sale deepens the loss. Use the contribution-margin ratio to find break-even revenue: fixed costs ÷ contribution-margin ratio. And use it to rank products by how efficiently each funds overhead — the highest-revenue line is often not the most valuable once variable costs are stripped out.
FAQ
What's the difference from gross margin? Gross margin subtracts COGS (including some fixed costs); contribution margin subtracts only variable costs, making it the right tool for incremental decisions.
Can contribution margin be negative? Yes — if price is below variable cost. Then every sale loses money and volume makes it worse.
How does it find break-even? Break-even units = fixed costs ÷ contribution margin per unit.
Is a higher contribution margin always better? Usually, but check volume and fixed-cost structure — a high-margin niche product may not cover large overheads on its own.
Related: Margin · Break-even · Unit economics Reviewed: 2026-08-02 · Sources: managerial accounting canon