Opportunity cost
Opportunity cost is the value of the best alternative you give up when you make a choice. The true cost of anything isn’t just its price — it’s everything you could have done with the same time, money, or attention instead.
✦ Foundational — cross-referenced 28× across this reference (20 related ideas · 1 comparisons · 7 hubs) · The State of Thinking 2026 →
How it works
Every “yes” is a “no” to everything else you could have done with that resource. Reckoning the foregone best alternative reveals the real cost the sticker price hides.
The most expensive costs never appear on any invoice.
How to use it
- Judge a purchase or commitment against the best other use of that money or time — not against zero.
- When something is “free,” ask what your time spent on it is worth elsewhere.
- Prioritise by comparing alternatives, not by whether something is “worth it” in isolation.
Worked example
A “free” two-hour meeting isn’t free. Those two hours could have shipped a feature, closed a sale, or rested you for tomorrow. The meeting’s real cost is the most valuable of those foregone alternatives.
Where it fails
Over-applied, it breeds paralysis and FOMO — every choice mourns infinite alternatives. Reserve it for significant allocations of time and money, not every small decision.
- The value of the forgone alternative is usually estimated, not known — comparing a real option against an imagined one systematically flatters whichever you already prefer.
- It assumes alternatives are actually available to you at the moment of choice; a theoretically better option you cannot access has no real cost.
- Constant alternative-counting itself consumes attention — the opportunity cost of computing opportunity costs on small decisions exceeds their stakes.
The counter-model: The sunk cost fallacy — Opportunity cost looks forward at what the next unit of time or money could earn; the sunk-cost fallacy is the backward-looking error it corrects — together they force decisions on future value only.
How to apply it, step by step
- Take one significant commitment of time or money you are about to make.
- Name the single best alternative use of that same time or money.
- Estimate what that alternative would plausibly return.
- Compare the chosen option against the alternative, not against doing nothing.
- Proceed only if the choice still beats its best alternative; otherwise switch.
The deeper point
The most expensive costs never appear on any invoice. Opportunity cost is invisible by design — which is exactly why it dominates the decisions people get most wrong, and why "but it was free" is so often a trap.
Frequently asked
- What is opportunity cost in simple terms?
- What you give up by choosing one option over another — the value of the best thing you could have done instead with the same time or money.
- How is opportunity cost different from sunk cost?
- Opportunity cost is about the future alternative you forgo; sunk cost is money already spent and unrecoverable. One should guide decisions; the other should be ignored.
- How do you use opportunity cost in decisions?
- Compare each option against the best alternative use of the resource, not against doing nothing — the real cost is the foregone best option.
Biases this model helps counter
Related
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Chesterton's fence
Scrap the pointless meeting and the small problems it caught early become crises.
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- Thinking, Fast and Slow — Daniel Kahneman
- The Art of Thinking Clearly — Rolf Dobelli
- The Great Mental Models, Volume 1 — Shane Parrish
- Poor Charlie’s Almanack — Charlie Munger
- Super Thinking — Gabriel Weinberg & Lauren McCann
- Seeking Wisdom — Peter Bevelin
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Cite this page
ReadGlobe. (2026). Opportunity cost. https://readglobe.com/model/opportunity-cost/
"Opportunity cost." ReadGlobe, 29 May 2026, readglobe.com/model/opportunity-cost/.
Primary source: Wikipedia
Editorial synthesis © ReadGlobe 2026, drawing on the mental-models tradition (Charlie Munger, Farnam Street) and the primary sources for each model. · Last reviewed 2026-05-29.