Reserve Ratio Calculator

Understanding the Reserve Ratio and Reserve Requirements

The reserve ratio is the proportion of total customer deposits that a commercial bank or financial institution must hold in vault cash or on deposit at the central bank (such as the Federal Reserve). Set by monetary policy authorities, the reserve requirement ensures bank liquidity, protects depositor funds, and controls the overall expansion of money supply in a fractional-reserve banking system.

Key Concepts in Fractional-Reserve Banking

• Required Reserves: The minimum liquid reserve dollar amount a bank is legally mandated to hold based on its deposit liabilities.
• Excess Reserves: Capital reserves held by a bank above and beyond the minimum legal requirement. Excess reserves represent funds available for lending to businesses and individuals.
• Money Multiplier: The theoretical maximum amount of broad commercial bank money created by one unit of excess reserve money:

$$\text{Money Multiplier} = \frac{1}{\text{Reserve Ratio}}$$

Reserve Ratio Formulas

To calculate required reserves and excess reserves for a bank:

$$\text{Required Reserves} = \text{Total Deposits} \times \left(\frac{\text{Required Reserve Ratio}}{100}\right)$$

$$\text{Excess Reserves} = \text{Total Reserves Held} - \text{Required Reserves}$$

$$\text{Max Money Expansion} = \text{Excess Reserves} \times \text{Money Multiplier}$$

Macroeconomic Impact of Reserve Ratios

Central banks lower reserve requirement ratios to boost economic liquidity during slowdowns, enabling commercial banks to extend more loans and stimulate investment. Conversely, raising reserve requirements restricts credit availability, reducing monetary expansion to curb inflationary pressures.