Answer:
Provided by total capital, which is equal to interest bearing debt in favor of the company, plus stockholder's equity like preferred stock and common stock.
The debt-to-capital ratio formula is:
Debt-to-Capital Ratio = Total Liabitilies / Total Capital
If the company does not have any interest bearing debt in its favor, then, the formula can be written as:
Debt-to-Capital Ratio = Total Liabilities / Stockholder's Equity