1.8 The Circular Flow and GDP

The Circular Flow Model

The circular flow model shows how money, goods, and services move between households, firms, the government, and the foreign sector through the product market and factor (resource) market. Households provide factors of production (land, labor, capital) to firms and receive income; firms provide goods/services to households in exchange for spending. Money flows in the opposite direction of real goods/resources.

Defining GDP

Gross Domestic Product (GDP) is the total market value of all final goods and services produced within a country's borders in a given time period. It excludes intermediate goods (to avoid double counting), used goods, financial transactions (like stocks), and nonmarket/illegal activity. GDP measures only newly produced output.

Two Ways to Calculate GDP

The expenditure approach: GDP = C + I + G + Nx (Consumption + Investment + Government spending + Net exports). The income approach sums all income earned producing goods (wages, rent, interest, profit). In theory both approaches yield the same GDP because one person's spending is another's income — reflecting the circular flow.

Key terms

Circular Flow Model

A diagram showing how money, resources, and goods/services flow between households, firms, government, and the foreign sector.

GDP

The total market value of all final goods and services produced within a country's borders in a given period.

Expenditure Approach

GDP = C + I + G + Nx (Consumption + Investment + Government spending + Net exports).

Intermediate goods

Goods used to produce final goods; excluded from GDP to avoid double counting.

Factor market vs. Product market

Factor market: households sell resources (land, labor, capital) to firms. Product market: firms sell goods/services to households.

Try an AP-style question

In the circular flow model, households supply…

1. factors of production to firms
2. goods and services to firms
3. taxes to foreign nations
4. loans to the government only