The terms good debt and bad debt have been repeated so many times in personal finance content that they have almost lost their meaning. A mortgage gets called good debt. Credit card balances get called bad debt. Student loans float somewhere in the middle depending on who you ask. The labels are useful as a starting point but the reality is more context-dependent than the categories suggest.
What makes debt potentially useful
Debt that funds something likely to grow in value, or that generates income, or that has a low enough interest rate that the opportunity cost of avoiding it entirely is higher than the cost of carrying it, can work in your favor. A mortgage on a property in a stable market is the classic example. The asset can appreciate over time and the interest rate, especially on older fixed mortgages, can be lower than inflation in some periods. A business loan used to grow revenue is another. The debt is doing something productive with the money.
What makes debt genuinely costly
High-interest consumer debt, particularly credit card balances carried month to month, works in exactly the opposite direction. The things you buy with it almost never increase in value. A dinner on a credit card you carry a balance on costs meaningfully more than the menu price once the interest is calculated. A television bought on a store card at 29 percent APR costs substantially more by the time the balance is paid. The item depreciates. The debt does not. That gap is what makes this kind of borrowing costly in a way that compounds quietly.
Student loans are complicated
Student loans occupy genuinely complicated territory. A degree that significantly increases earning power over a career can justify meaningful borrowing. But the debt-to-expected-salary ratio matters enormously. Borrowing $80,000 for a degree in a field where starting salaries average $35,000 is a different calculation than borrowing $40,000 for one where starting salaries average $70,000. The degree itself does not determine whether the debt was worth it. The earning outcome relative to the cost does.
Interest rate is the clearest signal
If you want a simple heuristic that cuts through the good debt and bad debt framing, use the interest rate. Debt under 5 or 6 percent, especially fixed rate debt on an asset, is generally manageable and sometimes strategically sensible to carry rather than pay off aggressively. Debt above 10 percent, and especially above 15 percent, is expensive in a way that demands priority attention regardless of what it was used for. The interest rate is not the only factor but it is the most honest one.
The good debt and bad debt framing is most useful when it helps you evaluate a new borrowing decision clearly. It is least useful when it becomes a post-hoc justification for debt you already have and do not want to deal with. At that point the label does not change the interest accruing on the balance.