Tier 1 Capital Ratio: Definition, Formula, and Example

The Tier 1 capital ratio measures a bank’s core capital relative to its risk-weighted assets.

It is one of the main ratios regulators use to judge whether a bank has a strong enough capital cushion to absorb losses without immediately threatening depositors or the wider financial system.

How It Works

A simplified form is:

Tier 1 capital ratio = Tier 1 capital / risk-weighted assets

Tier 1 capital generally includes the highest-quality capital, such as common equity and disclosed reserves, subject to regulatory definitions and adjustments.

Risk-weighted assets are not just total assets. They adjust exposures for perceived risk, so safer assets usually carry lower weights than riskier loans or positions.

Worked Example

Suppose a bank has:

• Tier 1 capital: $12 billion
• risk-weighted assets: $100 billion

Its Tier 1 capital ratio is 12%.

That means it has $12 of core capital for every $100 of risk-weighted assets.

Scenario Question

A reader says, “If a bank has a large asset base, it must have a strong Tier 1 capital ratio.”

Answer: No. The ratio depends on both the amount of core capital and the size and risk profile of the bank’s assets.

Related Terms

• Capital Adequacy Ratio: A broader regulatory capital measure that includes more than just Tier 1 capital.
• Basel III: Basel rules shape how banks define and report regulatory capital.
• Risk-Weighted Assets: The denominator in the Tier 1 capital ratio.
• Reserve Requirement: A different banking safeguard that should not be confused with capital ratios.
• Leverage Ratio: Another capital strength measure that does not rely on risk weights in the same way.

FAQs