In simple terms
A friendly intro before the formal notes — no formulas yet.
Opportunity cost
Whenever you choose one thing you give up the next best thing you could have had instead. That sacrifice is the opportunity cost, and it exists because resources are scarce.
Spending a Saturday at a football match means the next best plan — a day at the beach — is lost. The beach is the opportunity cost, whatever the ticket cost.
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Scarcity forces a choice between alternative uses of a resource.
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The next best alternative not chosen is the opportunity cost.
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Measure it in the thing given up — hours, goods, output — not just money.
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On a PPC, moving along the curve shows that opportunity cost directly.
Explore the concept
Use the live diagram and synced steps — play it or tap a step card to walk through.
1 more simulation for this topic — run them in the Simulations section below
Simulations
Every simulation here runs the real model — try the steps on a card, then check what you see against the notes.
1 simulation
- GeoGebraCore2281 1.3
Production possibility frontier
A curved frontier for goods X and Y with a movable point E, a Productionfrontier slider and two tick boxes that switch the view.
Try this
- Slide point E along the curve and say what is given up: more of good X always means less of good Y.
- Drag E inside the curve: here more of both goods is possible, so nothing need be given up.
- Move the Productionfrontier slider: with more resources the whole set of choices widens.
Look for Scarcity is the frontier itself; opportunity cost is the amount of one good forgone to get more of the other as you move along it.
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At a glance — side by side
Compare key properties side by side — ideal for exam contrasts.
Opportunity cost for different decision makers
| Decision maker | Example choice | Opportunity cost |
|---|---|---|
| Consumer | Buys a concert ticket with $60 | The trainers the $60 would have bought |
| Worker | Takes an extra evening shift | The leisure time, or the wage of the next best job |
| Producer | Uses a production line for vans | The cars the line would have made |
| Government | Spends $50 million on a hospital wing | The road the budget would have built |
| Saver | Keeps savings as cash | The interest a bank account would have paid |
Consumer
Example choice
Opportunity cost
Worker
Example choice
Opportunity cost
Producer
Example choice
Opportunity cost
Government
Example choice
Opportunity cost
Saver
Example choice
Opportunity cost
Full topic notes
Formal explanation with the rigour you need for the exam.
What opportunity cost means
Because wants are unlimited and resources are finite, choosing one use for a resource means giving up another. Economists call the value of the next best alternative forgone the opportunity cost of the choice. The word next matters: it is the single best alternative you did not take, not the sum of everything you could have done.
Opportunity cost is measured in the alternative itself — hours, goods, output — rather than in money. If a farmer uses a field for wheat, the opportunity cost is the barley the field could have grown, not the price of the seed.
Opportunity cost = the next best alternative forgone when a choice is made.
It exists because resources are scarce and wants are unlimited.
It is measured in what is given up, not simply in money spent.
Only the next best alternative counts — one alternative, not all of them.
Opportunity cost for consumers, workers and producers
A consumer with a fixed income who buys a concert ticket gives up the trainers that money would have bought. A worker who takes a job in a shop gives up the wage from the next best job offer, or the leisure time the hours would have provided. A student who stays in education gives up the earnings they could have had — one reason governments subsidise schooling.
A producer faces opportunity cost whenever it allocates capital and labour. A car factory that switches a production line to vans gives up the cars that line would have made. The same idea decides whether a firm should keep money in the bank or invest it: the interest forgone is the opportunity cost of the investment.
Consumers: the good or service not bought with the same income.
Workers: the wage of the next best job, or leisure time given up.
Producers: the output not made with the same factors of production.
Savers and investors: the interest or return forgone on the alternative use of funds.
When a question gives you figures, state the opportunity cost in those units: '$8 of wages' for a student who skips a shift, '200 houses' for a government that builds a hospital. 'The money' on its own never scores.
Opportunity cost for governments
Governments face the sharpest opportunity costs because their budgets are large and their choices affect everyone. Money spent on a new motorway cannot be spent on hospitals; land used for an airport cannot be used for housing. Every spending decision therefore invites the question what else could this have provided?
This is why governments use cost–benefit analysis and why opposition parties argue about priorities rather than totals. A government that cuts taxes also faces an opportunity cost: the public services the revenue would have funded.
Government spending on one project means less spending elsewhere — the forgone project is the opportunity cost.
Tax cuts have an opportunity cost too: the services the revenue would have paid for.
Public debate about budgets is largely debate about opportunity cost.
A well-reasoned answer names the specific alternative, e.g. '500 teachers' rather than 'other things'.
Opportunity cost and the production possibility curve
A production possibility curve (PPC) draws opportunity cost. Each point on the curve shows the maximum of one good that can be produced for a given amount of the other. Moving along the curve to produce more of good X means giving up some of good Y — that sacrifice is the opportunity cost, and it can be read from the axes.
The curve usually bows outward because resources are not equally suited to both goods: as more and more land is switched to wheat, each extra tonne costs more barley. A point inside the curve has no opportunity cost in the short run — idle resources can be used — which is why unemployment is seen as a waste.
Moving along a PPC shows the opportunity cost of one good in terms of the other.
A bowed-out PPC means opportunity cost rises as more of one good is made.
Points inside the curve use resources inefficiently; moving to the curve costs nothing in forgone output.
Economic growth shifts the curve outward and lowers the opportunity cost of any given choice.
For a 6-mark 'analyse' question, define opportunity cost, apply it to the decision in the question, then show the trade-off on a PPC sketch with labelled axes. For an 8-mark 'discuss' question, add that the decision may still be worthwhile if the benefits exceed the alternative forgone.
Worked examples
See the formulas applied — reveal one step at a time, like the exam.
A student chooses to study economics for an hour instead of working a part-time job paying $8 an hour. What is the opportunity cost of studying?
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Step 1 — Identify the alternatives: the hour could be spent studying or working. The next best alternative to studying is the hour of paid work.
A government has a budget of $50 million. It can build a new hospital wing for $48 million or a new road for $50 million. The hospital wing is expected to treat 20 000 extra patients a year; the road would save commuters 10 000 hours a week. The government chooses the hospital wing.
(a) State the opportunity cost of the decision. (b) Explain why the opportunity cost is not $48 million. (c) Suggest how the government might decide which option is better.
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Step 1 — Opportunity cost (a): the next best alternative forgone is the road, so the opportunity cost is the road and its benefit — roughly 10 000 commuter hours saved each week. (The $2 million left over could still be spent, but the road itself can no longer be built.)
How it all connects
The big idea sits in the middle — tap a linked idea to explore the link.
Tap a linked idea to see how it connects back to the main topic — that connection is what examiners reward.
Glossary
Key terms for this topic — skim now; the Check step will test them.
- Opportunity cost
The next best alternative forgone when a choice is made.
- Free good
A good that is not scarce, such as air, so using it has no opportunity cost.
- Economic good
A good made from scarce resources, so producing it has an opportunity cost.
- Cost–benefit analysis
Comparing the benefits of a decision with the benefits of the next best alternative to decide whether it is worthwhile.
Sort it out
One statement at a time, say which heading it belongs under. Every statement comes from this lesson’s side-by-side comparison.
The interest a bank account would have paid
Quick check
Write your answer first, then compare it with the model one — the gap is what you would have lost.
Teach it back
If you can explain it simply, you own it — gaps here are marks you’d lose.
Teach it back
Explain this topic as if teaching a friend. We name the gaps an examiner would still dock.
Revision flashcards
Guess first, then flip — retrieval beats re-reading.
Key takeaways
Review these before you close the topic — retrieval beats re-reading.
Opportunity cost = the next best alternative forgone when a choice is made.
It exists because resources are scarce and wants are unlimited.
It is measured in what is given up, not simply in money spent.
Only the next best alternative counts — one alternative, not all of them.
Practice — then mark it
The whole point: a real Cambridge question, marked mark-by-mark.
Mark an opportunity cost question
Mark an opportunity cost question
Extra simulations & links
PhET, GeoGebra and other curated tools — open in a new tab.
Frequently asked
Checkpoint
One marked question is worth ten re-reads — close the loop before you move on.
Reading it isn’t knowing it — prove it.
Before you move on: do Mark an opportunity cost question on paper, snap a photo, and get examiner-style feedback on exactly where you win and lose marks.
Discuss Opportunity cost
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