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What is opportunity cost? The cost of what you give up

Opportunity cost is the value of the best alternative you give up when you choose. Worked through for a four-year degree, a small business and a free concert ticket.

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Opportunity cost is the value of the next-best alternative you give up when you make a choice. If an evening spent studying means missing a film you'd have enjoyed, the film is the opportunity cost of the studying. It counts what a choice really costs, not just the money that changes hands, so it includes time, forgone earnings and anything else that had to be left aside. Only the single best alternative counts, not every option you passed over.

In short

  • The cost of anything is the best alternative it displaces, whether or not money changes hands.
  • Much of the cost of a degree is not tuition but the earnings given up while studying.
  • Opportunity cost looks forward: money already spent and gone is not part of it.

What does opportunity cost mean?

Because resources are scarce, choosing one use of them rules out others. OpenStax's Principles of Economics puts it in a line: "opportunity cost is the value of the next best alternative." Its example is a student, Alphonso, with a weekly budget, for whom a $2 burger costs four 50-cent bus tickets. The price tag says $2; the opportunity cost is four bus rides he can no longer take.

The idea is old. The French writer Frédéric Bastiat built an essay of 1850, What Is Seen and What Is Not Seen, around it. When a boy breaks his father's window, the six francs paid to the glazier are seen. What is not seen is what the father would have bought instead: new shoes to replace his worn-out ones, or another book for his library. Opportunity cost is the economist's name for the unseen half. It is the reason economics begins with choices rather than with money.

How do you work out the real cost of a degree?

A four-year degree is the classic worked example, because the largest cost is the one that never appears on a bill. The formula is:

Opportunity cost of the degree = tuition, fees and books + earnings given up while studying − earnings made while studying.

Room and board are left out, because a student would have to live and eat somewhere anyway. Only the extra cost of student housing, if any, counts. Here is one illustrative case for a student at a public university in their home state, with figures to show the method, not a forecast for anyone.

Item Per year Four years
Published tuition and fees, public four-year, in-state, 2025–26 $11,950 $47,800
Books and supplies (assumed) $1,200 $4,800
Earnings given up, working full time instead (assumed) $35,000 $140,000
Less part-time earnings while studying (assumed) −$8,000 −$32,000
Opportunity cost $40,150 $160,600

The tuition figure is the College Board's average for 2025–26, held flat for four years for simplicity. The forgone earnings are set below the US Bureau of Labor Statistics' 2025 median for full-time workers aged 25 and over with a high school diploma, $966 a week, or about $50,000 a year, because workers who are just starting out usually earn less than the median. Even so, the earnings given up, net of part-time pay, come to $108,000, about two thirds of the total and more than twice the tuition.

The same BLS table shows why many people judge the cost worth paying: in 2025, the median full-time worker with a bachelor's degree earned $1,578 a week, about $612 more than one with only a high school diploma. Whether a given degree pays for a given person depends on the field, the cost, whether they finish, and what they'd have done instead. This shows the method; it isn't advice about anyone's education.

What is the opportunity cost of an hour?

Time is where opportunity cost is easiest to forget. Suppose a freelance designer can bill clients $40 an hour, and keeps $30 after tax. Spending three hours cleaning the house, when a cleaner would charge $75, costs her $90 of forgone income, so hiring the cleaner and working instead leaves her $15 better off. The calculation holds only if the alternative is real: if no client would pay for those three hours, the opportunity cost of her cleaning is her leisure, not $90.

Small decisions work the same way. Driving 40 minutes across town to save $10 on a purchase is worth it only if those 40 minutes, plus the fuel, are worth less to you than $10. People often treat their own time as free, which is one reason they make trips like that and later wonder why the week vanished.

Why is opportunity cost different from accounting cost?

Accountants record explicit costs, the money actually paid out. Economists add implicit costs, the opportunity costs of resources a business already owns, as OpenStax explains. The gap can turn a profit into a loss.

Take a baker who runs her own shop. After paying for flour, rent, staff and equipment, the shop's books show a profit of $60,000 for the year. But she could have earned a $70,000 salary managing someone else's bakery, and the $100,000 of savings tied up in her ovens could have earned about $4,000 a year in a savings account. Her accounting profit is $60,000; her economic profit is $60,000 − $70,000 − $4,000, or −$14,000. On paper the shop makes money. Counted against her best alternative, it costs her $14,000 a year. She may stay anyway, for independence or the hope of growth, but she now knows the price of that choice.

What do people most often get wrong about opportunity cost?

Even economists get it wrong. At the American Economic Association's 2005 meeting, Paul Ferraro and Laura Taylor asked 199 economists with PhDs a short question. You have a free ticket to an Eric Clapton concert that you can't resell. The same night, Bob Dylan is playing; a ticket costs $40, and you'd pay up to $50 to see him. What is the opportunity cost of seeing Clapton: $0, $10, $40 or $50? The answer is $10, the $50 of enjoyment from Dylan minus the $40 you'd have paid. Only 43 of the 199, or 21.6%, chose it, the authors reported, fewer than random guessing would have given.

The common mistakes fall into four kinds:

  • Free means costless. The Clapton ticket cost nothing, but using it costs the next-best evening.
  • Adding up every option. If you choose a film over both a concert and a dinner, the opportunity cost is whichever of those you valued more, not both together.
  • Counting only money. Time, attention and forgone chances are costs even when no payment is made.
  • Counting the past. Money already spent and unrecoverable isn't given up by any choice you make now. Letting it steer the decision is the sunk cost fallacy, which is close to the opposite mistake: a cost that should be ignored, treated as one that counts.

Where does opportunity cost lead next?

Opportunity cost is the hinge between scarcity and most of the rest of economics. Decisions are usually about one more of something, so opportunity cost is weighed a unit at a time, the subject of marginal thinking. And because the opportunity cost of making a thing differs from person to person and country to country, trade lets each side specialize in what costs it least to give up. That is comparative advantage, and it rests entirely on comparing opportunity costs rather than raw skill.

Check yourself

  • Why are room and board left out of the opportunity cost of a degree, while lost earnings are counted?
  • In the Clapton and Dylan question, why is the answer $10 and not $0 or $40?
  • How can a business show an accounting profit and an economic loss in the same year?

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