Contribution margin formula
Contribution margin is the amount by which a product's selling price exceeds its total variable cost per unit; it is the money each sale contributes first to fixed costs and then to profit.[1]
The ratio is handy when a business sells many products: a 40% ratio means every extra $1 of sales adds $0.40 toward fixed costs and profit, whatever the units are.
Contribution margin vs gross margin
Contribution margin subtracts only variable costs, while gross margin subtracts cost of goods sold, which can include fixed production overhead and leaves out variable selling costs.
| Contribution margin | Gross margin | |
|---|---|---|
| Subtracts | All variable costs (production and selling) | Cost of goods sold |
| Fixed factory overhead | Not subtracted | Included in COGS |
| Sales commissions, card fees, shipping | Subtracted | Not subtracted (operating expenses) |
| Used for | Break-even, pricing a special order, product mix | Financial statements, pricing against peers |
A seller on a marketplace should treat the platform's commission and payment processing as variable costs: they rise with every sale. The gross margin calculator handles the financial-statement view.
Break-even point and margin of safety
Break-even units are fixed costs divided by contribution margin per unit: $15,000 ÷ $20 = 750 units, or $37,500 of sales.[2] Selling 1000 units leaves a margin of safety of 250 units, 25% of sales: the drop in sales the business can absorb before it starts losing money. The break-even calculator draws the chart and adds a target profit.
Operating leverage
The degree of operating leverage is total contribution margin divided by operating income; at 1000 units it is 4.00, so a 10% rise in sales lifts operating income by about 40%.[3]
| Units | Sales | Contribution | Operating income | Leverage |
|---|---|---|---|---|
| 800 | $40,000 | $16,000 | $1,000 | 16.00 |
| 1000 | $50,000 | $20,000 | $5,000 | 4.00 |
| 1200 | $60,000 | $24,000 | $9,000 | 2.67 |
Leverage works both ways. A business with high fixed costs and a high contribution ratio gains quickly above break-even and loses quickly below it. To test a price change against volume, use the price increase calculator; to see the per-unit price that covers fees and a target margin, use the selling price calculator.
Frequently asked questions
What is contribution margin?
It is the selling price minus the variable costs of one unit: the amount each sale adds toward fixed costs and profit.
How do you calculate the contribution margin ratio?
Divide contribution margin per unit by the selling price, or total contribution margin by total sales. $20 ÷ $50 = 40%.
Is contribution margin the same as gross profit?
No. Gross profit subtracts cost of goods sold, which can include fixed overhead; contribution margin subtracts every variable cost and no fixed cost.
Can contribution margin be negative?
Yes, when variable cost exceeds the price. Each extra sale then increases the loss, and there is no break-even point.
What counts as a variable cost?
Any cost that rises with each unit sold: materials, piece-rate labor, packaging, sales commissions, marketplace and card fees, and outbound shipping.
Sources
- Principles of Accounting, Volume 2: Managerial Accounting, 3.1 Contribution margin per unit, ratio and total
- Principles of Accounting, Volume 2: Managerial Accounting, 3.2 Calculate a Break-Even Point in Units and Dollars
- Principles of Accounting, Volume 2: Managerial Accounting, 3.5 Margin of Safety and Operating Leverage