What the number means
Opportunity cost compares one path with another. A calculation may assume the choice was available, affordable, executed at a quoted price and held continuously. Every one of those assumptions can be wrong.
Taxes, financing, maintenance, fees, dilution, dividends and the alternative use of money can change the answer. Good calculators list what they include and exclude.
When not to calculate
Relationships, health, safety, time with family and many career choices should not be forced into a dollar figure. Sometimes ‘unquantifiable’ is the accurate result.