Opportunity cost (Opportunitätskosten)

Level 1 · Basics

German termOpportunitätskosten

Used byDiscount rate · Education as capex on human capital · Total cost of ownership (TCO) · Rent-vs-buy framework · Commute cost accounting · Sunk cost

Opportunity cost is the value of the best alternative you give up when you commit money, time, or effort to one option instead. Opportunitätskosten (opportunity cost) is not a fee or a loss on paper — it's what the next-best use of the same resource would have delivered. Every euro, hour, or unit of attention spent one way is a euro, hour, or unit of attention not spent another way.

Why it matters

Opportunity cost underlies most personal-finance trade-offs, even when no invoice shows it. Almost every allocation of a limited resource is at bottom an A-versus-B choice: committing money, time, or attention to A means the value B would have delivered is the real cost of A, whether or not any cash changes hands. Cash sitting in a 0%-interest Girokonto (checking account) has an opportunity cost equal to the return it could have earned elsewhere, even though no statement lists it as an expense. Car ownership, rent-vs-buy decisions, education spending, and a longer commute for higher pay all involve giving up one path to take another — the cost is what the road not taken would have been worth.

The concept differs from an out-of-pocket cost, which is money actually paid. A €30,000 car purchase has an out-of-pocket cost of €30,000 and an opportunity cost equal to what that €30,000 would have returned if invested instead — two separate numbers, both real. Ignoring the second one makes "free" or "already paid for" options look cheaper than they are.

Worked examples

1. Cash sitting idle. €10,000 sits in a checking account paying 0% interest. A savings alternative offers an illustrative 2% per year. After one year, the idle cash has an opportunity cost of €10,000 x 2% = €200 — not a fee charged to the account, but the return forgone by not moving the money. Over five years, assuming the rate holds, the gap compounds to roughly €1,041 versus simple non-compounding growth of €1,000 — the exact figure depends on how the alternative compounds, but the direction is the same: idle cash has a real, if invisible, cost.

2. Commuting for higher pay. A job offer pays €4,200 gross per month, €500 more than a closer position, but adds one hour of commuting each way, five days a week — roughly 20 extra hours per month. Valuing that time at, say, €15 per hour (an illustrative rate a reader can substitute with their own) gives an opportunity cost of 20 x €15 = €300 per month in time given up. Against the extra €500 in pay, the trade-off nets out to roughly €200 per month before taxes, plus wear on the discretionary hours the commute removes from evenings or family time — a cost no payslip shows.

3. Choosing between two purchases with the same budget. €2,000 set aside can fund a course that plausibly raises earning power, or upgrade a home office. Spending it on the office means the opportunity cost is whatever the course track would have returned; spending it on the course means the opportunity cost is the value of a better workspace. Neither option has a hidden fee — the cost is what the unchosen option would have been worth.

Opportunity cost is closely related to, but distinct from, sunk cost — money or effort already spent that cannot be recovered regardless of the choice made now. Opportunity cost looks forward, at what a decision forgoes; sunk cost looks backward, at what a past decision cannot get back. The same framework applies to total cost of ownership (the full cost of holding an asset over time, not just its purchase price) and to a rent-vs-buy comparison, where the opportunity cost of a home down payment is a recurring line in the analysis.

Check yourself

You keep €5,000 in a checking account paying 0% interest for one year instead of moving it to an account paying an illustrative 3% per year. What is the opportunity cost, in euros, of keeping the money in the checking account for that year?

You buy a €20,000 car outright with cash instead of financing it. Which statement correctly separates the car's out-of-pocket cost from its opportunity cost?

The out-of-pocket cost is €20,000, and there is no opportunity cost because you paid cash instead of taking a loan.The out-of-pocket cost is €20,000, and the opportunity cost is the return that €20,000 could have earned if invested instead.The opportunity cost is €20,000, and there is no out-of-pocket cost since it was a one-time purchase.

A remote job pays €200 less per month than an in-office job, but the in-office job requires a commute that costs 10 hours a month. If you take the in-office job for the higher pay, what is the opportunity cost of that choice?

The €200 in extra monthly pay you receive.The value of the 10 hours a month you no longer have because of the commute.The total monthly salary of the in-office job.

Which of the following represent an opportunity cost, as opposed to an out-of-pocket cost or a sunk cost? Select all that apply.

The interest a savings account would have paid on cash left idle in a checking account.The €25,000 price actually paid for a car.The salary difference given up by choosing a lower-paying job with better hours.A €50 non-refundable course deposit already paid before deciding whether to attend.