Financial glossary
Opportunity Cost
In plain English
The value of the best alternative you give up when choosing how to use money, time, or another limited resource.
Opportunity cost
Opportunity cost is the benefit you give up by choosing one use of money over the best available alternative. It is not always a bill, so it is easy to omit from a comparison.
Putting $80,000 into a home down payment may build equity and reduce the mortgage, but that cash can no longer earn a market return in a diversified portfolio. Renting may cost more each month yet leave more cash invested. Neither result is automatic; the answer depends on return, appreciation, taxes, maintenance, transaction costs, risk, and time.
The rent vs. buy calculator treats the down payment and closing cash as the renter’s investable alternative. It also invests whichever side has the monthly cost advantage. This makes opportunity cost visible without assuming that an investment return is guaranteed.
Related calculators
- Rent vs. Buy CalculatorCompare renting and buying with mortgage, PMI, HOA, equity, appreciation, rent growth, selling costs, and invested cash.
- Investment Fee CalculatorSee how an annual expense ratio reduces your ending portfolio through direct fees and lost compounding across decades of regular contributions.