Managerial — Excel guide
Inward-facing accounting: how costs behave, where breakeven sits, and which costs should (and shouldn't) drive decisions.
Cost behavior & contribution margin
Fixed costs don't move with volume (rent); variable costs do (materials). Contribution margin = price − variable cost per unit: what each sale contributes toward fixed costs, then profit.
Costs that fool decision-makers
SUNK costs are spent and unrecoverable, irrelevant to what happens next, however painful. OPPORTUNITY cost is the value of the best alternative you give up, invisible on statements, central to decisions.
Variance analysis
Actual vs budget, split into price and quantity effects: did we pay more per unit, or use more units? Favorable/unfavorable labels beat raw differences because they carry direction.
Capital budgeting bridges
Payback period is the quick risk screen; NPV and IRR are the real decision tools, see the NPV & IRR cheat sheet on the finance side. WACC is the discount rate a company's NPVs should clear.