Field note
Contribution Margin for Better Decisions
See how each sale contributes to fixed costs and profit, with examples for services and products.
The useful distinction
Contribution margin is revenue minus variable costs. It shows how much a sale contributes to fixed costs and eventually profit, making it useful for product mix and promotion decisions.
A simple working method
Track it per unit, order, or customer. Include costs that actually change with the sale—materials, shipping, transaction fees, and commissions—and keep fixed overhead out of the numerator.
Worked example
A service sells for 500 and incurs 120 of contractor time, 20 in processing fees and 10 in delivery supplies. Variable cost is 150, so contribution is 350 and the contribution margin ratio is 70%.
Common mistakes
- Including fixed rent in one unit but not another
- Leaving commissions or payment fees out
- Assuming every customer requires the same delivery effort
When this number can mislead
Contribution is most useful when cost behavior is classified consistently. A cost can be fixed within one range and become variable or step-based at a higher volume, so document the period and capacity assumption.
Frequently asked questions
Is contribution margin the same as gross margin?
Not always. Contribution focuses on costs that change with the sale; gross margin follows the chosen accounting classification of cost of goods sold.
Can labor be a variable cost?
Yes, when labor hours or contractor payments change with each order. Keep salaried or capacity costs classified consistently for the decision.
How does contribution help product mix?
When fixed costs are already committed, higher contribution per constrained unit can help prioritize offers, subject to demand and capacity.
Decision checklist
- Define the unit and measurement period.
- Include costs that change with the sale.
- Check capacity and customer demand before ranking products.
Definition and formula context: U.S. SBA break-even guidance.
Write down the period, costs included, and whether figures are before or after discounts. Clarity makes a calculation reusable.
Use the profit margin calculator → · Review methodology and sources