AP® Macroeconomics · Unit 2 · Topic 2.1
The Circular Flow Model
The circular flow model shows how spending and income chase each other endlessly between households and firms, so every dollar spent by one party is income for another.
Picture two loops running opposite directions between households and firms. In the outer loop, real stuff moves: households supply labor, land, and capital to firms through resource markets, and firms supply goods and services back to households through product markets. In the inner loop, money moves the other way: firms pay wages, rent, and profit to households for those resources, and households pay money back to firms for the goods and services they buy. Follow the money loop and you see why spending equals income: the dollar a household spends at a store becomes revenue for the firm, which becomes wages for the firm's workers, who are themselves households.
Add government and the foreign sector and the loops get more realistic. Households and firms both pay taxes to government and receive spending back from it, and the economy sends exports out to foreign buyers while pulling imports in. Taxes, savings, and imports are leakages, money that exits the simple household-firm spending stream. Government spending, investment, and exports are injections, money that enters the stream from outside. A healthy circular flow just needs total leakages to equal total injections, not zero leakages.
This answers the savings worry directly. Saved money does not vanish, it leaks into banks and financial markets, which lend it back out as investment, an injection that returns it to firms. That round trip is exactly why GDP measured by total income equals GDP measured by total expenditure: every dollar leaking out through saving, taxes, or imports eventually reenters through investment, government spending, or exports, keeping the two measurements of the same flow equal.
Key terms
- Circular flow model
- A diagram showing how money, goods, and resources move continuously between households and firms.
- Leakage
- Money that exits the household-firm spending stream, such as savings, taxes, or spending on imports.
- Injection
- Money that enters the spending stream from outside it, such as investment, government spending, or exports.
- Resource market
- The market where households sell labor, land, and capital to firms.
- Product market
- The market where firms sell finished goods and services to households.
Watch it explained
- How it worksWalk me through the two loops of the circular flow running between households and firms.
- Going furtherWhat happens to the circular flow when government and foreign buyers are added to it?
- Common mistakeWhy doesn't money leaking into savings simply vanish from the economy?
- Ties togetherHow does the circular flow explain why the income and expenditure ways of measuring GDP agree?
Check yourself
End of topic.