The Money Supply: M1, M2, and Beyond

How economists measure the amount of money in an economy, and why the M1 and M2 distinction matters for reading the news.

When economists or news anchors talk about “the money supply,” it sounds like it should be a simple number - how much money exists. In reality, money comes in different forms that are easier or harder to actually spend, and economists track several different measures to capture that.

Why “how much money” isn’t one simple number

The money supply is the total amount of money circulating in an economy at a given time. But money isn’t just physical cash. It also includes the balance in a checking account, the balance in a savings account, and other financial holdings that can eventually be turned into cash. The question economists really care about is liquidity - how quickly and easily a given form of money can be used to make a purchase. Physical cash is about as liquid as it gets; a savings account is slightly less liquid, since you might need to transfer it first; a longer-term investment is even less liquid still.

M1: the most liquid measure

M1 captures the most liquid forms of money: physical currency in circulation and the funds sitting in checking accounts and similar readily-spendable accounts. If you can walk into a store and use it, or pull it directly from an ATM, it’s generally captured in M1. This measure gives economists a sense of how much money is immediately available for everyday spending.

Cash in hand versus cash a step away

Imagine two people each have $2,000. One keeps it in a checking account, ready to spend with a debit card at any moment. The other has it in a savings account that requires a transfer first, or in a small time deposit that can't be touched for a few months without a penalty. Both people have $2,000 in "money," but only the first amount counts toward M1. The second person's money still exists and still counts as part of the broader money supply - it just isn't as instantly usable.

M2: a broader picture

M2 includes everything in M1, plus somewhat less liquid forms of money: savings accounts, money market mutual funds, and small time deposits like short-term certificates of deposit. These funds aren’t quite as instantly spendable as cash or a checking account balance, but they can typically be converted into spendable money fairly quickly, without much hassle or penalty.

M2 is the measure most commonly referenced in economic news when reporters talk about “the money supply” growing or shrinking, because it captures a broader, more complete picture of the money households and businesses have available, even if some of it takes a small extra step to actually spend.

Why this distinction actually matters

Treating M1 and M2 as interchangeable

It's easy to assume any mention of "the money supply" refers to the same underlying number. But M1 and M2 can tell different stories at different times - M1 might grow quickly while M2 grows slowly, or vice versa, depending on how people are choosing to hold their money. A sharp rise in M2 without a matching rise in M1 might suggest people are saving rather than spending; watching only one measure can give an incomplete picture of what's actually happening in the economy.

Economists watch these measures partly because changes in the money supply can be an early signal of inflationary pressure, a theme covered in this curriculum’s inflation lessons - though the relationship is far from perfectly predictable, and modern economists debate how tightly money supply growth and inflation actually track each other.

Beyond M1 and M2

There are broader measures still, sometimes labeled M3 or similar, that capture even less liquid assets, such as larger institutional deposits. These broader measures are used less frequently in everyday economic reporting, but they exist for economists who want the fullest possible picture of everything that could, in principle, eventually become spendable money.

Key takeaways

The money supply isn't one simple number; economists track several measures based on liquidity.
M1 covers the most liquid money: physical cash and checking account balances.
M2 includes M1 plus less liquid holdings like savings accounts and money market funds.
M2 is the measure most commonly cited in everyday economic news.
M1 and M2 can move differently, and watching only one can give an incomplete picture.
Broader measures beyond M2 exist for capturing even less liquid forms of money.