GUIDE深度 · Deep dive
ROI, Gross Margin and Break-Even
ROI measures investment efficiency: (gain-cost)/cost; gross margin measures product profitability: (revenue-cost)/revenue; break-even asks how many units: fixed cost/(price-variable cost). Watch the denominators.
Formulas
ROI=(gain-cost)/cost x 100%.
Gross margin=(revenue-cost)/revenue x 100%.
Break-even=fixed/(price-variable).
Intuition
ROI denominator is investment.
Margin denominator is revenue.
Break-even denominator is contribution margin.
Label the numerator and denominator before dividing; most exam mistakes come from picking the wrong base.
FAQ
Can ROI and margin be compared?
Not directly; denominators and contexts differ.
Round break-even up?
In practice, round up to whole units.