contribution margin approach. Operating income is income or profit before income taxes. Contribution
margin is sales revenue minus total variable costs.
The operating income approach uses the following basic equation:
Operating income = Sales revenue – Variable expenses – Fixed expenses
Sales revenue is equal to the unit selling price times the number of units sold. Total variable costs equal
the unit variable cost times the number of units sold. Therefore, the operating income equation can also be
expressed as follows:
Operating income = (Price × Number of units) – (Variable cost per unit ×
Number of units) – Total fixed costs
Finally, the equation for a target profit is put in terms of units:
Units for a target profit = (Total fixed cost + Target income)/(Price – Variable cost per unit)
Cornerstone 16.2 (p. 827) shows how and why to calculate the units needed to break even and to achieve
a target profit.
By substituting the unit contribution margin for price minus unit variable cost in the operating income
equation, and solving for the number of units, the following break-even expression is obtained:
Number of units = Fixed costs/Unit contribution margin
To calculate the break-even point in sales revenue, variable costs are defined as a percentage of sales
rather than as an annual per unit sold. To express variable cost in terms of sales revenue, we compute the
variable cost ratio, which is the proportion of each sales dollar that must be used to cover variable costs.
The percentage of sales revenue remaining after variable costs are covered is the contribution margin
ratio. The contribution margin ratio is the proportion of each sales dollar available to cover fixed costs
and provide for profit.
The sales-revenue approach is computed by using the following equation:
Sales = (Total fixed costs + Operating income)/Contribution margin ratio
At break-even, operating income equals zero, so the equation becomes:
Break-even sales = Total fixed costs/Contribution margin ratio
Cornerstone 16.3 (p. 831) illustrates the calculation of break-even sales revenue and sales revenue needed
to achieve a target profit for Blazin-Boards Company.
II. AFTER-TAX PROFIT TARGETS
To determine the number of units that must be sold to reach an after-tax profit target, first convert the
after-tax profit to a before-tax profit target. To do this, divide the after-tax profit by (1 − Tax rate). Then,
the desired before-tax profit can be used in the target profit formula presented on the following page.