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Opportunity Cost Calculator

See what a purchase costs you in foregone investment growth.

What is opportunity cost?
Opportunity cost is the value you give up by choosing one use of money over another — here, what a lump sum could have grown to if invested instead of spent.
How is opportunity cost calculated?
By projecting the same amount forward at an assumed investment return over the same time horizon using compound growth; the difference between spending it and investing it is the opportunity cost.

Your numbers

$

A purchase or expense you’re considering, instead of investing it.

$

e.g. a recurring subscription or habit, instead of investing it each month.

%

Enter your numbers and press Calculate to see your results.

What Is Opportunity Cost?

Opportunity cost is the value you give up by choosing one use of money over another. This calculator takes a one-time amount, an optional recurring monthly amount, and an assumed investment return, then projects what that money could have grown to if invested instead of spent, compounding monthly.

This is not a judgment on the purchase — some spending is worth it. The point is transparency: seeing the growth foregone makes it possible to weigh a purchase against its real alternative, not just its price tag.

How this is calculated

What-if future value = FV(amount, monthly amount, return, years) — the growth foregone by spending instead of investing.

Assumptions

  • Assumes the money would otherwise have earned the entered return, compounding monthly.
  • This is not a judgment on the purchase — it’s a transparency tool for what the alternative would have been worth.
  • Returns are a fixed average; actual investment returns vary and can be negative.

Frequently asked questions

Does this mean I should never spend money?
No. Opportunity cost is one input to a decision, not a verdict. Plenty of spending is worth more than its invested alternative — this tool just makes that trade-off visible.
What return rate should I assume?
There is no single correct number. A long-run diversified market average is a common reference point, but returns are never guaranteed and can be negative in any given period.
Does opportunity cost apply to paying off debt too?
Yes, in reverse — paying down high-interest debt has a "return" equal to the interest rate avoided, which is often higher than a typical investment return.

What should you calculate next?

Opportunity Cost Calculator answers one part of the picture. These pick up where it leaves off.

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This calculator provides estimates for educational purposes only and is not personalized financial advice. Rates, taxes, and financial products change — verify with providers and qualified professionals.