Measuring the Size of the Economy

Measuring the Size of the Economy: Introducing Gross Domestic Product

Macroeconomics is an empirical subject, so the first step toward understanding it is to measure the economy.

How large is the U.S. economy? The size of a nation’s overall economy is typically measured by its gross domestic product (GDP), which is the value of all final goods and services produced within a country in a given year. The measurement of GDP involves counting up the production of millions of different goods and services—smart phones, cars, music downloads, computers, steel, bananas, university educations, and all other new goods and services produced in the current year—and summing them into a total dollar value. This task is straightforward: take the quantity of everything produced, multiply it by the price at which each product sold, and add up the total. In 2014, the U.S. GDP totaled $17.4 trillion, the largest GDP in the world.

Each of the market transactions that enter into GDP must involve both a buyer and a seller. The GDP of an economy can be measured either by the total dollar value of what is purchased in the economy, or by the total dollar value of what is produced. There is even a third way, as we will explain later.