Money Supply
The money supply is the total amount of money in an economy, measured in layers such as the monetary base, M1 and M2. It includes currency and bank deposits, and central banks watch it as one input into monetary policy.
How much money is out there — and how fast is it growing? Economists have argued about the money supply's link to inflation for a century. Central banks track it in several measures, from cash and bank reserves to broad deposits. This entry explains the main measures, how they change and what they mean for markets.
- Category
- Fundamentals and Macroeconomics
- Reading time
- 3 min
- Also called
- M2 money supply, Monetary base, Money stock
- Updated
The money supply in plain words
Currency and balances in checking and savings accounts are included in many measures of the money supply.1
Standard measures include the monetary base (currency plus banks' reserves at the Fed), M1 and M2.1
Money supply is a key variable for macroeconomic performance and a tool in implementing monetary policy.2
How the money supply is measured, step by step
Monetary base
Currency in circulation + bank reserves at the central bank.
M1
Currency held by the public plus liquid deposits.
M2
M1 plus savings, small time deposits and money market funds. See Money Market Fund.
Track growth
Year-over-year changes.
Compare with output
Money growth vs GDP growth. See Gross Domestic Product.
Watch policy
Central bank actions change the base. See Open Market Operations.
Worked examples
Example 1 — Growth rate
+5%M2 rises from $20 trillion to $21 trillion in a year.
| Growth | $1tn ÷ $20tn = 5% |
Analysts watch money growth as one signal of how loose or tight conditions are.2
Example 2 — Money vs output
Inflation riskMoney grows 10% while real output grows 2%.
| Gap | 10% − 2% = 8 points |
When money grows much faster than output for long, inflation pressure can build. See Inflation.
Example 3 — Monetary base
$5.5tnCurrency in circulation $2.3tn, bank reserves $3.2tn.
| Monetary base | $2.3tn + $3.2tn = $5.5tn |
The monetary base is currency in circulation plus reserve balances held at the Fed.1
Money supply measures
| Aspect | Includes | Liquidity |
|---|---|---|
| Monetary base | Currency + bank reserves | Highest |
| M1 | Currency + liquid deposits | Very high |
| M2 | M1 + savings and similar | High |
| See also | Quantitative easing | Quantitative Easing and Tightening |
Why investors watch the money supply
Inflation outlook
Fast money growth can feed inflation.
Liquidity conditions
More money can support asset prices. See Liquidity.
Central bank policy
QE and QT change the base. See Quantitative Easing and Tightening.
Crypto narratives
Fiat supply vs fixed supply. See Bitcoin (BTC).
Advantages and disadvantages
Advantages
- Shows how much money circulates.
- Useful context for inflation and liquidity.
- Published regularly by central banks.
Disadvantages
- Link to inflation is unstable.
- Definitions change over time.
- Velocity of money varies.
Going deeper
Read as far as you need. Each level builds on the one before it.
Not just cash
Beginner
Most money is bank deposits, not physical notes and coins.1
Monetary aggregates
Intermediate
Money supply is grouped into monetary aggregates, from the narrowest to the broadest measures.2
Velocity
Advanced
Inflation depends on how fast money is spent as well as how much exists; when velocity falls, money growth may not raise prices. See Macroeconomics.
Common mistakes
Assuming money growth means instant inflation
The link is loose and lagged.
Mixing measures
M1, M2 and the base differ.
Ignoring definition changes
Series can break.
Forgetting velocity
Spending speed matters too.
Check your understanding
Test yourself before moving on. Each answer comes with an explanation.
Key points to remember
- The money supply is the total money in an economy.
- Key measures: monetary base, M1, M2.
- It includes currency and bank deposits.
- Central banks influence it through policy.
- Its link to inflation is real but unstable.
Frequently asked questions
Who controls the money supply?
Does more money always mean inflation?
Where can I see M2 data?
Further learning
- Open Market Operations
How central banks change money.
- Quantitative Easing and Tightening
Large-scale money creation.
- Inflation
The price effect.
- Liquidity Trap
When more money doesn't help.
Sources
This article is written in our own words. The sources below support the specific facts, rules and figures marked with a number in the text. Links open the original publisher’s page.
- Federal Reserve Board. What is the money supply? Is it important? (opens in a new tab) Checked .
- Corporate Finance Institute. Money Supply (opens in a new tab) Checked .
Educational content, not financial advice. Examples use hypothetical prices and simplified costs; actual fees, margin rules and regulations vary by broker, market and country. We are not affiliated with any publisher linked above. Last reviewed . Report an error or request a source credit.