Understanding maximum money creation requires linking bank reserve requirements to how deposits expand through lending. This page explains the “maximum” case, the core formula you must know, and how to interpret it correctly.

Core idea: maximum money creation

Banks operate in a fractional reserve system, meaning they keep only a fraction of deposits as reserves and can lend the rest. When a bank loan is spent and the funds are redeposited, deposits can expand repeatedly across the banking system.

A sequence of T-account balance sheets illustrating how a loan creates a deposit and how required reserves limit the amount a bank can lend. As the loan proceeds are deposited at another bank, that bank’s deposits and reserves rise, enabling further (smaller) rounds of lending. This diagram links the “fractional reserve” idea to the repeated redepositing mechanism assumed in the maximum money creation model. Source

This subsubtopic focuses on the maximum expansion possible, which depends entirely on the required reserve ratio and assumes away real-world leakages.

Key term: required reserve ratio (rr)

The required reserve ratio is the fraction of certain deposits that banks are legally required to hold as reserves (rather than lend out).

In the “maximum” scenario, banks hold no excess reserves and households hold no additional currency from the funds created by lending.

The maximum money multiplier

The maximum money multiplier tells you the largest multiple by which deposits (and therefore the money supply, in the simple model) can expand from an initial increase in reserves.

A higher required reserve ratio forces banks to keep more of each deposit, shrinking the amount available to lend each round, which reduces the multiplier.

This relationship is central: the maximum money multiplier equals the reciprocal of the required reserve ratio. Therefore, a larger multiplier allows greater money creation, and a larger $rr$ produces a smaller multiplier.

Calculating maximum money creation (what “maximum” means)

When the banking system receives an initial increase in reserves, the simple model treats it as the “fuel” for deposit creation. In AP Macroeconomics, maximum money creation is typically expressed as the maximum change in deposits (and, in this simplified setting, the maximum change in the money supply measure tied to deposits).

The key is to treat the multiplier as converting an initial reserves injection into the largest possible total expansion of deposits.

Conceptually, the process works like this:

A round-by-round deposit expansion table (with a stated required reserve ratio) showing how each successive bank keeps required reserves and lends the remainder. The table makes the “maximum” setup visible: loans are fully redeposited, so deposits expand in smaller and smaller rounds toward a finite limit. This is the numerical intuition behind why total deposits approach the maximum implied by the reserve ratio. Source

• A deposit arrives in the banking system (directly or via central bank actions that raise reserves).

• Banks must keep $rr$ of deposits as required reserves.

• The remainder is lent out, spent, and (in the maximum case) fully redeposited.

• Each round creates smaller new loans, but the cumulative total approaches a finite maximum determined by $1/rr$.

Interpreting “larger multiplier”

Because $mm = 1/rr$:

A graph of cumulative (accumulated) deposits across successive rounds of lending for multiple reserve requirements. The curves flatten out as they approach a maximum, illustrating that deposit creation is a convergent geometric process rather than unlimited growth. Lower required reserve ratios produce a higher limiting level of deposits, consistent with $mm = 1/rr$. Source

• If $rr$ falls, banks are required to hold a smaller fraction of deposits, so they can lend more each round, raising maximum money creation.

• If $rr$ rises, banks must hold more reserves per dollar of deposits, reducing lending per round and lowering the maximum expansion.

This is why the reserve requirement (when used) is considered a powerful lever in the simple deposit expansion model.

Conditions required for the maximum (exam precision)

The phrase maximum money creation is conditional. It assumes:

• Banks lend out all funds beyond required reserves (no excess reserves).

• Borrowers redeposit the proceeds fully into the banking system (no currency drain).

• The required reserve ratio applies uniformly and the relevant deposits are reservable.

Common pitfalls to avoid

• Using a percentage for $rr$ instead of a decimal in formulas.

• Treating the multiplier as guaranteed rather than an upper bound.

• Forgetting that “maximum” depends on the absence of leakages that reduce redepositing and lending.