Which metric represents the overall value of a firm without considering its capital structure?

The metric that represents the overall value of a firm without considering its capital structure is enterprise value. Enterprise value provides a comprehensive measure of a company's total value, taking into account not only its equity but also its debt and subtracting cash and cash equivalents. This makes it a useful metric for investors since it reflects what it would cost to acquire the entire firm, including its liabilities.

In contrast, equity value only accounts for the company's net assets available to shareholders and does not consider the implications of debt. Net income is a measure of profitability and is not a valuation metric. The debt ratio focuses specifically on the firm’s leverage and the proportion of debt relative to its assets, which is not directly related to the overall value assessment of the firm.

Thus, enterprise value is the most suitable measure for evaluating a firm’s worth in a way that does not depend upon its capital structure.