What it means
When a bank receives a deposit, it keeps a fraction as a reserve and lends out the rest. The borrower spends the loan, the seller deposits it into another bank, and that bank again keeps a fraction and lends the rest.
Each round creates new deposits, so a single initial deposit supports a much larger total. The deposit multiplier measures how many times the original deposit can be multiplied.
A lower reserve requirement means banks can lend more of each deposit, so the multiplier is larger. A higher reserve requirement shrinks the multiplier.
The idea matters to business leaders because it explains how lending creates money and how central bank policy influences credit. If a central bank raises the reserve requirement, banks have less to lend and borrowing may become harder or more expensive.
If it lowers the requirement, credit can become more available. In practice the real-world multiplier is lower than the textbook figure.
Banks often hold extra reserves, borrowers keep some cash instead of depositing it, and loan demand may be weak. Many modern central banks also rely more on interest rates than on reserve requirements, so the simple formula is a teaching tool rather than a precise forecast.
Even so, the concept is useful for understanding why a small change in bank reserves can have a larger effect on the economy. It also helps explain why banks cannot lend unlimited amounts, since each new loan must be supported by reserves.
It is also worth separating the textbook model from how modern banks actually decide to lend. Today, many economists argue that banks first respond to loan demand and then find the reserves they need, rather than waiting for deposits to arrive.
The deposit multiplier remains a handy teaching device, but it should not be used to predict the exact effect of policy changes.
In practice
Real-world examples.
Example
A university economics lecturer uses a $50,000 deposit and a 20% reserve requirement to teach the concept. The multiplier is 5, so the maximum total deposits are $250,000, which shows students how lending expands the money supply.
Example
A central bank economist models what happens if the reserve requirement falls from 10% to 5%. The multiplier doubles from 10 to 20, which shows how much more credit the banking system could support in theory.
Example
A bank treasurer reviews why actual lending has grown by far less than the textbook figure suggests. She finds that customers are holding more cash and that the bank is keeping extra reserves for safety.
Formula
Calculation
Deposit multiplier = 1 / Reserve requirement ratio
Maximum total deposits created = Initial deposit x Deposit multiplier
Suppose a bank receives a new deposit of $100,000 and the reserve requirement is 10%. The deposit multiplier is 1 / 0.10 = 10. The maximum total deposits created across the banking system are $100,000 x 10 = $1,000,000, of which the original $100,000 is the first deposit and $900,000 is new money created through lending.Case study
Seen in the real world.
Eastbrook Bank is a fictional lender created for this illustrative case study. A new customer deposits $200,000, and the reserve requirement is 10%, so the bank keeps $20,000 and lends out $180,000 to a local bakery.
The bakery spends the loan on ovens, and the supplier deposits it in another bank. That bank keeps $18,000 and lends $162,000, and the process continues. In theory the original $200,000 supports up to $2,000,000 of deposits, but in reality the bakery's supplier keeps some of the payment in cash and the lending slows well short of that figure.
A year later, the central bank cuts the reserve requirement from 10% to 8%, and Eastbrook's treasurer recalculates. The multiplier rises from 10 to 12.5, so the same $200,000 deposit could in theory support up to $2,500,000 of deposits. In practice the bank only lends an extra $150,000 because local demand is modest, which shows why the formula sets an upper limit rather than a forecast.
Watch out
Common mistakes.
- Treating the multiplier as a guaranteed outcome. It is a theoretical maximum, and real-world results are usually lower.
- Mixing up the reserve requirement with the capital requirement. Reserves are cash held against deposits, whereas capital is the bank's own funding that absorbs losses.
- Using the percentage instead of the decimal. A 10% requirement must be entered as 0.10, giving a multiplier of 1 / 0.10 = 10, whereas entering 10 would wrongly give 1 / 10 = 0.1.
Questions
People also ask.
What happens to the multiplier if the reserve requirement is zero?
The simple formula breaks down because it would imply an infinite multiplier. In practice, banks are limited by capital rules, liquidity needs and loan demand.
Is the deposit multiplier the same as the money multiplier?
They are closely related, and the terms are often used loosely as the same thing. The money multiplier is usually broader, because it also accounts for cash held by the public and extra reserves.
Why does it matter to a business?
It helps explain how credit conditions respond to central bank decisions. A tighter policy can make loans harder to obtain, which affects investment plans.
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