Glossary term
Reserve Ratio
A reserve ratio is the share of reservable deposits that a bank must hold as reserves rather than lend or invest.
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What Is a Reserve Ratio?
A reserve ratio is the share of reservable deposits that a bank must hold as reserves rather than lend or invest. In central banking, it is the percentage applied to certain deposit liabilities to determine required reserves.
The reserve ratio is a monetary and banking-policy tool. It affects how much liquidity banks must keep available, how the payment system is supported, and how central banks structure money-market operations.
Key Takeaways
- A reserve ratio sets required reserves as a percentage of certain deposits.
- Required reserves can be held as vault cash or balances at a central bank, depending on the system.
- A higher reserve ratio ties up more bank liquidity.
- A lower reserve ratio frees more balance-sheet capacity, though lending still depends on capital, demand, and risk.
- In the United States, reserve-requirement ratios have been set at zero since March 2020, but the concept remains important.
Formula
The basic calculation is:
If a bank has $100 million of reservable deposits and the reserve ratio is 10%, required reserves are $10 million. Those reserves are not the same as bank capital. Reserves are liquid assets for settlement and requirements; capital is a loss-absorbing cushion.
How It Works
Reserve requirements apply to specific liabilities defined by regulation. A central bank or banking authority determines what counts as reservable and what percentage applies. Banks then hold the required amount in eligible forms, such as vault cash or central-bank balances.
Historically, reserve ratios were used to influence credit creation and liquidity. Raising the ratio could reduce funds available for lending. Lowering it could release liquidity. Modern monetary policy often relies more heavily on interest-rate tools, reserve-balance management, and central-bank facilities, but reserve ratios remain part of the banking vocabulary.
Reserve Ratio Versus Capital Ratio
Ratio | What it measures | Main purpose |
|---|---|---|
Reserve ratio | Required reserves relative to reservable deposits | Liquidity and monetary-policy operations |
Capital ratio | Capital relative to assets or risk-weighted assets | Loss absorption and solvency |
Liquidity coverage ratio | High-quality liquid assets relative to stressed outflows | Short-term liquidity resilience |
Why the U.S. Setting Can Confuse People
Since March 2020, U.S. reserve-requirement ratios have been set at zero. That does not mean banks hold no reserves. Banks still hold reserve balances for payment settlement, liquidity management, and monetary-policy reasons. It means the regulatory reserve requirement itself is not currently forcing a positive minimum based on transaction accounts.
This distinction matters because the phrase reserve ratio can refer to a formal requirement, while bank reserves as a balance-sheet item can still be very large. A zero reserve requirement is not a zero-reserve banking system.
What It Can Signal
A change in reserve ratios can signal a shift in monetary or regulatory policy. In some systems, lowering reserve ratios is used to ease liquidity pressure or encourage lending. Raising them can restrain credit growth or increase liquidity buffers. The effect depends on the banking system, whether reserves are scarce or abundant, and whether banks are constrained by capital, funding, or borrower demand.
Multiplier Misread
Introductory textbooks often connect reserve ratios to a simple money multiplier. Real banking is more complicated. Banks also need capital, willing borrowers, profitable lending opportunities, funding stability, and risk appetite. A lower reserve ratio alone does not force banks to lend.
Bank-Level and System-Level Effects
At the bank level, reserve requirements affect how much liquid capacity must be held against certain liabilities. At the system level, reserve policy interacts with central-bank balance-sheet operations, payment settlement, and short-term rates. The same ratio can have different effects in a scarce-reserves system than in an abundant-reserves system.
The Bottom Line
The reserve ratio is a banking rule that links deposits to required reserves. It is most useful when read alongside bank reserves, capital ratios, liquidity rules, and the central bank's operating framework.