p. 100. Accounting: A Very Short Introduction (2014).
I understand the green sentence beneath, but not the fractional formula for BEP containing CPU in red? What's the intuition for the latter?
Contribution
The ‘contribution’ is the amount that a particular product line helps towards covering fixed costs and making a profit. The contribution is measured as: Sales − Variable costs. This can also be calculated per unit of production. The contribution per unit (CPU) is:
$\color{red}{CPU = \text{Selling price per unit} − \text{Variable cost per unit}}$
That is, taking the selling price for one unit of production, and then deducting all the variable costs for that one unit of production, gives the contribution per unit.
Break-even point (BEP)
$\color{forestgreen}{\text{The break-even point is the volume of production at which the firm makes zero profit.}}$ Therefore, the break-even point is the level at which all costs (including fixed costs) can be paid for. The formula is:
$BEP = \dfrac{\text{Total fixed costs}}{\color{red}{\text{Contribution per unit (CPU)}}}$
So, above the break-even point, any extra items sold will generate profit. Every unit that is produced and sold in excess of the break-even point will generate profit of the amount of the CPU. The total profit made is:
Units in excess of break-even point × CPU
If the firm does not reach break-even point, this implies that it has not yet covered fixed costs and will therefore make a loss. The size of the loss will be the number of units under the break-even point, multiplied by the CPU.
The break-even point can be derived using the formula given above, or by drawing up a chart such as Figure 15.