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The break-even math
Every sale first pays for the cost of making that one item; whatever remains is the contribution margin that chips away at fixed costs. Break-even happens when enough margins have accumulated to cover the fixed block: fixed costs ÷ contribution margin per unit. A $20 margin against $10,000 of fixed costs needs exactly 500 sales — each sale after that drops the full $20 to the bottom line.
Using break-even to make decisions
Break-even is a lever you can pull from either side. Raising price widens the margin and lowers the units needed, but usually costs some volume; trimming the variable cost (a cheaper supplier, less waste) does the same without touching the shelf price. Cutting fixed costs lowers the bar outright. Compare the units required against realistic demand — a break-even point the market cannot support is a signal to redesign the plan, not to try harder.
Contexto local: España
Datos locales clave para cálculos financieros en España — difieren de los valores estándar de EE. UU.:
- IVA: Tipo general 21 %, reducido 10 % (hostelería), superreducido 4 % (alimentos básicos). Los precios al consumidor lo incluyen.
- IRPF (2025): Tramos progresivos del 19 % al 47 % según la comunidad autónoma, con mínimo personal y familiar de 5.550 €.
- Cotizaciones: A cargo del trabajador ≈ 6,7 % del bruto (contingencias comunes 4,7 %, desempleo 1,55 %, formación 0,1 %, horas extra) más la retención de IRPF.
- SMI 2025: 1.184 € al mes en 14 pagas (16.576 €/año) — las pagas extra de julio y diciembre son habituales.
- Propina: Voluntaria; lo habitual es dejar un 5–10 % o redondear la cuenta.
Actualizado: octubre 2026 · valores de 2025, fuentes oficiales arriba.
Preguntas frecuentes
What counts as a fixed cost?
Costs that do not move with each sale over the period: rent, salaries, insurance, software subscriptions, loan payments. A cost that only appears when you produce a unit belongs in the variable column.
Why round the break-even units up?
A fraction of a sale cannot cover its share of fixed costs, so 500.2 units still means 501 sales in practice. The exact figure is shown too, since it is the one to use for revenue math.
Can I use this for a service business?
Yes — treat each engagement or client hour as a “unit.” Fixed costs are your monthly overhead, price is the fee, and variable costs are whatever delivering that unit costs you.