Contribution Margin Calculator
Calculate contribution margin in dollars and as a percentage of revenue to determine how much each sale contributes toward covering fixed costs and generating profit.
How to use this tool
- Enter total revenue (or selling price per unit), total variable costs (or variable cost per unit), total fixed costs and units sold (optional — for per-unit output) in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your contribution margin and the full breakdown beneath it.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
CM = Revenue − Variable Costs
CM Ratio = CM / Revenue × 100%
Break-Even Sales = Fixed Costs / CM Ratio
How it works
Contribution margin measures the revenue remaining after all variable costs are subtracted — the amount available to cover fixed costs and ultimately generate profit. The CM ratio expresses this as a percentage of revenue, making it easy to compare across products or scale up to higher sales volumes.
Break-even sales is derived by dividing total fixed costs by the CM ratio: it represents the revenue level at which operating income equals zero. This calculator treats all inputs as either purely fixed or purely variable; in practice, some costs have mixed behavior and may require further analysis.
Worked example
$50,000 revenue, $30,000 variable costs, $10,000 fixed costs
- Revenue = $50,000, Variable costs = $30,000, Fixed costs = $10,000, Units = 1,000.
- Contribution margin = $50,000 − $30,000 = $20,000.
- CM ratio = $20,000 / $50,000 = 40%. CM per unit = $20,000 / 1,000 = $20.
- Operating income = $20,000 − $10,000 = $10,000. Break-even sales = $10,000 / 0.40 = $25,000.
Contribution margin = $20,000 (40% ratio); break-even at $25,000 in sales.
Common mistakes to avoid
- Including fixed costs in variable costs, understating the contribution margin and inflating the break-even point calculation.
- Using total revenue and total costs without correctly splitting semi-variable costs (e.g., utilities with a fixed base plus a usage charge) into fixed and variable components.
- Treating a positive contribution margin as profit -- CM only confirms each sale covers variable costs; fixed costs must still be covered before profit is earned.
Key terms
- Contribution Margin (CM)
- Revenue minus all variable costs; the amount each dollar of sales contributes toward covering fixed costs and profit.
- CM Ratio
- Contribution margin expressed as a percentage of revenue; indicates how many cents of every revenue dollar become contribution margin.
- Variable Costs
- Costs that change proportionally with production or sales volume, such as direct materials and direct labor.
- Fixed Costs
- Costs that remain constant regardless of production volume within a relevant range, such as rent and salaries.
- Break-Even Point
- The revenue level at which total contribution margin exactly equals total fixed costs, resulting in zero operating profit or loss.
Frequently asked questions
- What is the difference between contribution margin and gross profit?
- Gross profit deducts COGS, which typically includes both variable production costs and fixed manufacturing overhead. Contribution margin deducts only variable costs, making it more useful for break-even analysis and short-run pricing decisions.
- Can the contribution margin ratio exceed 100%?
- No. CM ratio = CM / Revenue, and CM = Revenue - Variable Costs. Unless variable costs are negative, the ratio is always between 0% and 100%.
- How do I use the break-even sales figure?
- Break-even sales is the revenue needed so CM exactly covers fixed costs. Revenue above break-even generates operating profit at the CM ratio rate. For a target profit P, required sales = (Fixed Costs + P) / CM Ratio.