Bank capital is the difference between a bank's assets and its:

1. Capital requirements are one category of bank regulation. 2. Capital is measured from the two sides of the balance sheet. 3. Bank capital is the difference between a bank's assets and its liabilities. 4. So the answer is liabilities. _Source: OpenStax Principles of Macroeconomics 3e (CC BY 4.0), Ch 15 'Monetary Policy and Bank Regulation', sections 15.1-15.5_