~2 min read
Contribution margin is the selling price minus all variable costs. It is the per-unit engine of profit: every unit sold adds its contribution margin to the pool that covers fixed costs. Once fixed costs are fully covered, every additional unit sold converts 100% of its contribution margin to profit.
Unit Contribution Margin (UCM) = Selling Price − Variable Cost per Unit
Contribution Margin Ratio (CM Ratio) = UCM ÷ Selling Price × 100
Break-Even Units = Fixed Costs ÷ UCM
Units to Hit Target Profit = (Fixed Costs + Target Profit) ÷ UCM
What counts as a variable cost?
Variable costs are those that increase directly with each unit produced or sold: - Materials, components, and raw ingredients - Payment processing fees (e.g., 2.9% + $0.30 per transaction) - Shipping and fulfillment costs - Sales commissions tied to each deal - Cloud hosting that scales per API call or user
Fixed costs do not vary with output: payroll, rent, annual software subscriptions, insurance, and depreciation.
CM ratio benchmarks by business type
| Business Type | Typical CM Ratio | Notes |
|---|---|---|
| SaaS | 70–85% | Low variable cost; hosting and payment fees are small |
| Consulting / services | 60–80% | Time is the variable cost |
| E-commerce | 30–55% | COGS, fulfillment, and returns reduce margin |
| Manufacturing | 25–50% | Raw materials dominate variable cost |
| Restaurants | 20–40% | Food, beverages, and hourly labor are variable |
Pricing decisions with contribution margin
If your CM ratio is low, you face a structural challenge: each sale contributes little toward the fixed cost pool. You either need high volume or a higher price. Increasing price by 10% while holding variable costs flat directly raises the CM ratio — the most powerful lever for early-stage businesses.
Running multiple pricing scenarios is the best use of this calculator: model the CM ratio at different price points and see the break-even units shrink as price rises.
Frequently asked questions
How is contribution margin different from gross margin? Gross margin (used in accounting) subtracts cost of goods sold (COGS), which may include some fixed manufacturing overhead. Contribution margin subtracts only purely variable costs. For product businesses with simple cost structures they are often similar, but for manufacturing they can differ significantly.
What is a good contribution margin ratio? It depends on the business model. SaaS companies typically target 70%+ CM ratios. E-commerce is viable at 35–50%. Below 20%, the business requires very high volume to generate meaningful profit and has little pricing flexibility.