Contribution costing is a way of looking at costs that separates variable costs (those that change with production) from fixed costs (those that stay the same). The contribution margin is the amount that each unit sold adds to covering fixed costs and then to profit.
| Concept | Formula |
|---|---|
| Contribution per unit | \$C = P - V\$ |
| Break‑even units | \$BE = \dfrac{F}{C}\$ |
| Profit | \$π = (P - V) \times Q - F\$ |
Imagine you run a cake shop. The price you charge for a cake is the sales price (P). The cost of flour, sugar, eggs, and butter is the variable cost (V) – it changes with each cake you bake. The rent for the shop and the salaries of the staff are fixed costs (F) – they stay the same no matter how many cakes you make.
When you sell a cake, the money left after paying for the ingredients is the contribution margin (C). This money first covers the shop’s rent and staff salaries. Once those are paid, any remaining contribution is profit.
Suppose:
Then:
| Feature | Contribution Costing | Absorption Costing |
|---|---|---|
| Treats fixed manufacturing costs as | Expenses (outside the cost of goods sold) | Part of the cost of goods sold (allocated to units) |
| Used for | Decision making, break‑even analysis, short‑term planning | Financial reporting, long‑term planning |
Remember:
• Contribution margin is calculated as Sales – Variable Costs.
• Break‑even units = Fixed Costs ÷ Contribution per unit.
• Use contribution costing for short‑term decisions like pricing, product mix, and special orders.
• In exam questions, look for words such as “variable”, “fixed”, “contribution”, “break‑even” to identify the correct approach.
• Show all steps clearly – write the formula, plug in the numbers, and state the final answer.
A company sells a product for £25. Variable cost per unit is £12 and fixed costs are £8,000. How many units must be sold to break even?
Answer: \$BE = \dfrac{8,000}{25-12} = 615.38 \approx 616\$ units.