One measure in the break-even model is that of fixed costs. In the traditional cost-accounting world, fixed costs may be determined by full costing or by variable costing.
Full costing assigns a portion of fixed production overhead charges to each unit of production, treating these as a variable cost. Variable costing, by contrast, treats these fixed production overhead charges as period charges; a portion of these costs may be included in the fixed costs allocated to the product. Thus, full costing reduces the denominator in the break-even model, whereas the variable costing alternative increases the denominator. Hence, as the fixed costs raise so does the break even point.