Revenue, costs, break-even and contribution: fixed and variable costs, total revenue and total cost, the calculation and interpretation of break-even output and the margin of safety, and contribution per unit.

What this dot point is asking

WJEC Unit 1 includes the core financial calculations: telling fixed from variable costs, working out total revenue and total cost, finding the break-even output and margin of safety, and calculating contribution. This is where the quantitative skills marks live, so you must be able to show the method, get the number and interpret it, not just define the terms.

The answer

Fixed and variable costs

The split matters because only variable costs change when output changes, which is the basis of contribution and break-even. Note that a cost is fixed in total but its share per unit falls as output rises (the rent is spread over more units), while a variable cost is roughly constant per unit but rises in total.

Revenue and profit

Total revenue is the money from sales: total revenue = selling price x quantity sold. Profit is what is left after costs: profit = total revenue - total cost. A firm makes a loss when total cost exceeds total revenue, breaks even when they are equal, and makes a profit when revenue is the greater.

Contribution

Break-even

The break-even output is the quantity at which total revenue exactly equals total cost, so the firm makes neither a profit nor a loss:

break-even output = fixed costs / contribution per unit.

Below break-even the firm makes a loss; above it, every extra unit adds its contribution to profit. Break-even can also be read off a break-even chart, where the total-cost line crosses the total-revenue line.

Margin of safety

The margin of safety shows how far sales can fall before the firm starts to make a loss:

margin of safety = actual (or budgeted) output - break-even output.

A large margin of safety means the firm is well above break-even and can absorb a fall in demand; a small margin means it is dangerously close to a loss.

Examples in context

Example 1. A high-fixed-cost gym. A new gym has high fixed costs (rent, equipment leases, staff) but a low variable cost per member, so its contribution per member is large and almost all of each membership fee above the small variable cost goes towards the heavy fixed costs. It must sign up a high number of members to break even, but once past break-even, additional members are very profitable. The example shows how the cost structure (high fixed, low variable) drives a high break-even point and a steep climb to profit.

Example 2. A market trader with low fixed costs. A Welsh market trader has low fixed costs (a cheap stall pitch) but a high variable cost per unit (stock bought wholesale), so contribution per unit is smaller. Their break-even quantity is low because fixed costs are small, making it easier to cover costs, but profit per extra unit is modest. The contrast with the gym shows how the balance of fixed and variable costs shapes both the break-even point and how quickly profit rises with sales.

Try this

Q1. Define the term contribution per unit. [2 marks]

• Cue. Selling price per unit minus variable cost per unit; the amount each unit sold contributes towards fixed costs and then profit.

Q2. A firm has fixed costs of £8,000, a selling price of £10 and variable costs of £6 per unit. Calculate its break-even output. [3 marks]

• Cue. Contribution = £10 - £6 = £4. Break-even = £8,000 / £4 = 2,000 units.