M1 and M2 vs Monetary Base (High-Powered Money)
M1 and M2 and Monetary Base (High-Powered Money) are two Money & Monetary Policy concepts in AP Economics that students often mix up. M1 and M2 are measures of the money supply; M1 is the most liquid money and M2 includes M1 plus less-liquid near-money. The monetary base, or high-powered money, is currency in circulation plus bank reserves, the money the central bank directly controls. Here is how they compare side by side.
M1 covers currency and checkable deposits. M2 adds savings deposits, small time deposits, and retail money market funds. M1 is used directly for transactions, while M2 captures money that can be spent after conversion.
It is called 'high-powered' because each dollar of base can support a larger change in the broader money supply through the multiplier as banks lend. The base differs from M1/M2: it includes bank reserves (not in M1) but excludes the deposit expansion that reserves enable. The Fed changes the base mainly through open market operations.
M1 and M2 vs the Monetary Base: What the Central Bank Creates and What Banks Create
| M1 and M2 | Monetary Base (High-Powered Money) | |
|---|---|---|
| Who creates it | Mostly commercial banks, which credit a new checkable deposit every time they write a loan | Only the central bank, through open market operations and lending to banks |
| What is inside | Currency held by the public plus checkable deposits, with savings deposits, small time deposits and retail money market funds added for M2 | Currency held by the public plus bank reserves, meaning vault cash and deposits held at the central bank |
| What is deliberately left out | Bank reserves never count, because households and firms cannot spend them | Deposits never count, because they are liabilities of commercial banks rather than of the central bank |
| Role in the money multiplier | The output, the quantity the multiplier produces | The input, the quantity the multiplier acts on |
| Effect of a $10 million open market purchase at a 10 percent reserve ratio | Can rise by up to $100 million, and only if banks lend out every excess dollar | Rises by exactly $10 million on the day the trade settles |
| Effect of one bank writing a new $500 loan | Rises by $500 the moment the deposit is credited to the borrower | Unchanged, because no new central bank liability was created |
| Degree of central bank control | Influenced, never set, since it depends on bank lending and on how much cash the public chooses to hold | Set almost exactly, since every unit of it is a central bank liability |
Bank reserves sit in the base and never appear in M1
The two measures overlap on exactly one item, currency held by the public, and disagree about everything else. Reserves are money banks hold, not money the public can spend, so reserves belong to the base and are excluded from every published money supply measure. Checkable deposits run the other way. They are counted in M1 and M2 and cannot be in the base, because the base counts only what the central bank itself owes. Sort each item that way and most exam questions about which measure moved answer themselves. Cash withdrawn from a bank swaps reserves for currency, so the base is unchanged, and it swaps a deposit for currency, so M1 is unchanged too. A transfer from a checking account into a savings account lowers M1, leaves M2 alone because M2 already contained both accounts, and leaves the base alone because no currency and no reserves changed hands. Neither transaction creates a single dollar of new money, which is the point those questions are usually built around.
One open market purchase moves the two by very different amounts
Say the central bank buys $10 million of bonds from a commercial bank. Reserves rise by $10 million immediately, so the monetary base rises by exactly $10 million, no more. With a required reserve ratio of 10 percent the simple money multiplier is 1 divided by 0.10, or 10, so the banking system can create up to $100 million of new checkable deposits as those reserves are lent out and redeposited. M1 can therefore rise by ten times the base change. Notice which number is certain and which is a ceiling. The base change is arithmetic, settled the moment the trade clears. The M1 change depends on banks choosing to lend and on the public choosing to redeposit rather than hold cash. Every leakage, whether banks holding excess reserves or households holding currency, shrinks the M1 result while leaving the $10 million base change untouched. The wording of the question is deliberate when it asks for the maximum change in the money supply, so an answer stating that the money supply will rise by $100 million, rather than that it can rise by at most $100 million, has turned a ceiling into a forecast.
The base can grow over a stretch when M2 shrinks
The multiplier makes the two measures look chained together, and they can still move in opposite directions. If the central bank buys bonds while banks park the proceeds as excess reserves instead of lending, the base grows and deposits do not. If borrowers are repaying loans faster than banks are writing new ones at the same time, deposits are being destroyed, so M2 actually falls while the base rises. Nothing about that story violates the multiplier, because the multiplier was always an upper bound rather than a prediction. The practical reading for an exam is that the base tells you what the central bank did and M1 and M2 tell you what the banking system and the public did in response. When a question describes banks holding unusually large excess reserves, it is telling you the multiplier has collapsed and that an injection into the base will land far short of the textbook maximum.
Frequently asked questions
Is the monetary base part of M1?
Only one piece of the monetary base sits inside M1, namely currency held by the public. Bank reserves make up the rest of the base, and reserves appear in no money supply measure at all, because households and firms cannot spend them. Neither measure contains the other. Treating the base as a smaller version of M1 costs the point on any question that moves reserves without moving deposits, such as a bank borrowing $2 million at the discount window, which lifts the base by $2 million and leaves M1 exactly where it was until that money is lent out.
Which quantity does the money multiplier apply to?
The money multiplier applies to the monetary base, and more precisely to the excess reserves created when the base grows. Multiply the change in excess reserves by 1 divided by the required reserve ratio to get the maximum change in checkable deposits, which is a change in M1. Applying the multiplier to M1 itself is the most common slip. The second most common is forgetting that when the central bank buys from the public rather than from a bank, the new deposit carries a required reserve charge, so excess reserves rise by less than the purchase price.
Does moving money from checking into savings change the money supply?
Moving $400 from a checking account into a savings account lowers M1 by $400 and leaves M2 exactly where it was, since M2 already contained both accounts. The monetary base does not move either, because no currency left the bank and total reserves are unchanged. Questions built on this transfer are testing whether you know which account belongs to which measure, not whether you can run a multiplier calculation.
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