← Management accounting to inform decision-making

The relevant range: when break-even assumptions stop holding

Break-even and target-profit formulas assume fixed costs and the selling price stay constant — but only within a "relevant range" of output, a distinction recent papers test directly.

What the relevant range means in practice

  • Fixed costs are only truly fixed WITHIN a certain range of output — beyond a machine's capacity, a business must buy another machine, adding a new step of fixed costs (a "step cost").
  • If a target-profit calculation asks for MORE units than the machine or facility can actually produce, that target is not achievable without further investment — an "explain whether it is achievable" question is testing exactly this check.
  • Always compare a calculated required volume against the STATED capacity constraint in the resources before concluding a target is realistic.
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Treating a target-profit calculation as automatically achievable

A calculation showing "54 units are needed" is not the same as "54 units are achievable". If the resources state a capacity limit (e.g. a machine that can produce at most 40 units a month), a required volume above that limit means the target cannot be met without further investment — say so explicitly rather than stopping at the arithmetic. Exam-style Checking a target against a seasonal pattern, not just a monthly average An average of 54 units/month is needed across the year, but sales are strongly seasonal. Do not stop at the annual average — check whether the low-season months alone could produce a shortfall large enough that even a strong high season cannot make it up. If the resources give a monthly sales pattern, compare it month by month against capacity, not just against the average. Conclude explicitly: achievable only if the seasonal shortfall is small enough to be recovered elsewhere, or not achievable if it is not. ✓ This is the Excellence-level version of the relevant-range check — testing the target against the ACTUAL pattern given, not the smoothed-out average.

Practise just this