What is contribution margin?

The answer

Contribution margin is what a sale leaves after paying its own variable costs: selling price minus variable cost per unit. That amount contributes first to fixed costs such as rent and salaries, and then to profit. As a ratio, it is contribution ÷ selling price × 100.

Contribution margin is the number behind break-even and sales targets. It tells you how much each sale really helps the business once the costs that come with that sale are paid.

The formula

Variable costs are the ones that rise with each sale: the goods or ingredients, packaging, card charges, delivery and sales commission. Fixed costs, such as rent, salaries and software, are not included; contribution is what pays for them. Use prices and costs without GST.

A worked example

An invented home bakery sells a celebration cake for ₹600. Ingredients cost ₹270 and the box and board ₹30.

If the bakery's fixed costs are ₹90,000 a month, it needs ₹90,000 ÷ ₹300 = 300 cakes, or ₹1,80,000 of sales, to break even. At 400 cakes, total contribution is 400 × ₹300 = ₹1,20,000, and profit is ₹1,20,000 − ₹90,000 = ₹30,000. Every cake beyond break-even adds its full ₹300 to profit. The full method, including shops with many products, is in how to calculate break-even point.

Contribution margin vs gross margin

The two are close cousins. Gross margin subtracts only the cost of the goods sold. Contribution margin also subtracts other costs that vary with each sale. For the cake, gross margin on ingredients alone would be ₹330 (55%), but the box is unavoidable for every cake, so contribution is ₹300 (50%). For a shop with few selling costs, the two figures are nearly the same; where card charges, delivery or commission are significant, contribution margin is the more honest guide. See how to calculate profit margin for gross margin.

What it is used for

• Break-even: fixed costs ÷ contribution per unit.
• Sales targets: (fixed costs + profit wanted) ÷ contribution margin ratio, as in setting a monthly sales target.
• Discount decisions: a discount comes straight out of contribution, so a small price cut can halve it.
• Product choices: an item with a high contribution per unit helps cover fixed costs faster.

Common mistakes

• Putting rent or salaries into variable costs, which understates contribution.
• Leaving out per-sale costs such as packaging or card charges, which overstates it.
• Including GST in the price.

Try your own numbers with the break-even calculator, which shows contribution per unit and the contribution margin ratio.

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General information, not legal, tax or financial advice. Published by Chameron Digital.