Measuring the size of the economy: gross domestic product (article) | Khan Academy (2024)

Read about GDP and how we measure it.

Key points

  • The size of a nation’s economy is commonly expressed as its gross domestic product, or GDP, which measures the value of the output of all goods and services produced within the country in a year.

*GDP is measured by taking the quantities of all final goods and services produced and sold in markets, multiplying them by their current prices, and adding up the total.

  • GDP can be measured either by the sum of what is purchased in the economy using the expenditures approach or by income earned on what is produced using the income approach.

  • The expenditures approach represents aggregate demand (the demand for all goods and services in an economy) and can be divided into consumption, investment, government spending, exports, and imports. What is produced in the economy can be divided into durable goods, nondurable goods, services, structures, and inventories.

  • To avoid double counting—adding the value of output to the GDP more than once—GDP counts only final output of goods and services, not the production of intermediate goods or the value of labor in the chain of production.

  • The gap between exports and imports is called the trade balance. If a nation's imports exceed its exports, the nation is said to have a trade deficit. If a nation's exports exceed its imports, it is said to have a trade surplus.

Introduction

To understand macroeconomics, we first have to measure the economy. But how do we do that? Let's start by taking a look at the economy of the United States.

The size of a nation’s overall economy is typically measured by its gross domestic product, or GDP, which is the value of all final goods and services produced within a country in a given year. Measuring GDP involves counting up the production of millions of different goods and services—smart phones, cars, music downloads, computers, steel, bananas, college educations, and all other new goods and services produced in the current year—and summing them into a total dollar value.

The numbers are large, but the task is straightforward:

Step 1: Take the quantity of everything produced.

Step 2: Multiply it by the price at which each product sold.

Step 3: Add up the total.

In 2014, the GDP of the United States totaled $17.4 trillion, the largest GDP in the world.

It's important to remember that 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 by the total dollar value of what is purchased in the economy or by the total dollar value of what is produced.

Understanding how to measure GDP is important for analyzing connections in the macro economy and for thinking about macroeconomic policy tools.

GDP measured by components of demand

$17.4 trillion is a lot of money! Who buys all of this production? Let's break it down by dividing demand into four main parts:

  • Consumer spending, or consumption
  • Business spending, or investment
  • Government spending on goods and services
  • Spending on net exports

What is meant by the word investment?

What do economists mean by investment? When talking about GDP, investment does not refer to the purchase of stocks and bonds or the trading of financial assets. It refers to the purchase of new capital goods—new commercial real estate, such as buildings, factories, and stores, as well as equipment, residential housing construction, and inventories.

Inventories that are produced this year are included in this year’s GDP—even if they have not yet sold. From the accountant’s perspective, it is as if the firm invested in its own inventories.

The table below shows how the four above components added up to the GDP for the United States in 2014. It's also important to think about how much of the GDP is made up of each of these components. You can analyze the percentages using either the table or the pie graph below it.

Components of US GDP in 2014: from the demand side
Components of GDP on the demand side in trillions of dollarsPercentage of total
Consumption$11.968.4%
Investment$2.916.7%
Government$3.218.4%
Exports$2.313.2%
Imports–$2.9–16.7%
Total GDP$17.4100%

A few patterns are worth noticing here. Consumption expenditure by households was the largest component of the US GDP 2014. In fact, consumption accounts for about two-thirds of the GDP in any given year. This tells us that consumers’ spending decisions are a major driver of the economy. However, consumer spending is a gentle elephant—when viewed over time, it doesn't jump around too much.

Investment demand accounts for a far smaller percentage of US GDP than consumption demand does, typically only about 15 to 18%. Investment can mean a lot of things, but here, investment expenditure refers to purchases of physical plants and equipment, primarily by businesses. For example, if Starbucks builds a new store or Amazon buys robots, these expenditures are counted under business investment.

Investment demand is very important for the economy because it is where jobs are created, but it fluctuates more noticeably than consumption. Business investment is volatile. New technology or a new product can spur business investment, but then confidence can drop, and business investment can pull back sharply.

If you've noticed any infrastructure projects—like road construction—in your community or state, you've seen how important government spending can be for the economy. Government expenditure accounts for about 20% of the GDP of the United States, including spending by federal, state, and local government.

It's important to remember that a significant portion of government budgets are transfer payments—like unemployment benefits, veteran’s benefits, and Social Security payments to retirees—that are excluded from GDP because the government does not receive a new good or service in return or exchange. The only part of government spending counted in demand is government purchases of goods or services produced in the economy—for example, a new fighter jet purchased for the Air Force (federal government spending), construction of a new highway (state government spending), or building of a new school (local government spending).

And finally, we must consider exports and imports when thinking about the demand for domestically produced goods in a global economy. First, we calculate spending on exports—domestically produced goods that are sold abroad. Then, we subtract spending on imports—goods produced in other countries that are purchased by residents of this country.

The net export component of GDP is equal to the dollar value of exports, X, minus the dollar value of imports M. The gap between exports and imports is called the trade balance. If a country’s exports are larger than its imports, then a country is said to have a trade surplus. If, however, imports exceed exports, the country is said to have a trade deficit .

If exports and imports are equal, foreign trade has no effect on total GDP. However, even if exports and imports are balanced overall, foreign trade might still have powerful effects on particular industries and workers by causing nations to shift workers and physical capital investment toward one industry rather than another.

Based on the four components of demand discussed above—consumption, C, investment, I, government, G, and trade balance, T —GDP can be measured as follows:

GDP=C + I + G + (X - M)

GDP measured by what is produced

Everything that is purchased must be produced first. Instead of trying to think about every single product produced, let's break out five categories: durable goods, nondurable goods, services, structures, and change in inventories. You can see what percentage of the GDP each of these components contributes in the table and pie chart below.

Before we look at these categories in more detail, take a look at the table below and notice that total GDP measured according to what is produced is exactly the same as the GDP we measured by looking at the five components of demand above.

Since every market transaction must have both a buyer and a seller, GDP must be the same whether measured by what is demanded or by what is produced.

Components of US GDP on the production side, 2014
Components of GDP on the supply side in trillions of dollarsPercentage of total
Goods
Durable goods$2.916.7%
Nondurable goods$2.313.2%
Services$10.862.1%
Structures$1.37.4%
Change in inventories$0.10.6%
Total GDP$17.4100%

Let's take a look at the graph above showing the five components of what is produced, expressed as a percentage of GDP, since 1960. In thinking about what is produced in the economy, many non-economists immediately focus on solid, long-lasting goods—like cars and computers. By far the largest part of GDP, however, is services. Additionally, services have been a growing share of GDP over time.

You are probably already familiar with some of the leading service industries, like healthcare, education, legal services, and financial services. It has been decades since most of the US economy involved making solid objects. Instead, the most common jobs in the modern US economy involve a worker looking at pieces of paper or a computer screen; meeting with co-workers, customers, or suppliers; or making phone calls.

Even if we look only at the goods category, long-lasting durable goods like cars and refrigerators are about the same share of the economy as short-lived nondurable goods like food and clothing.

The category of structures includes everything from homes to office buildings, shopping malls, and factories.

Inventories is a small category that refers to the goods that have been produced by one business but have not yet been sold to consumers and are still sitting in warehouses and on shelves. The amount of inventories sitting on shelves tends to decline if business is better than expected or to rise if business is worse than expected.

The Problem of Double Counting

GDP is defined as the current value of all final goods and services produced in a nation in a year. But what are final goods? They are goods at the furthest stage of production at the end of a year.

Statisticians who calculate GDP must avoid the mistake of double counting—counting output more than once as it travels through the stages of production. For example, imagine what would happen if government statisticians first counted the value of tires produced by a tire manufacturer and then counted the value of a new truck sold by an automaker that contains those tires. The value of the tires would have been counted twice because the price of the truck includes the value of the tires!

To avoid this problem—which would overstate the size of the economy considerably—government statisticians count just the value of final goods and services in the chain of production that are sold for consumption, investment, government, and trade purposes. Intermediate goods, which are goods that go into the production of other goods, are excluded from GDP calculations. This means that in the example above, only the value of the truck would be counted. The value of what businesses provide to other businesses is captured in the final products at the end of the production chain.

Counting GDP
What is counted in GDPWhat is not included in GDP
ConsumptionIntermediate goods
Business investmentTransfer payments and non-market activities
Government spending on goods and servicesUsed goods
Net exportsIllegal goods

Take a look at the table above showing which items get counted toward GDP and which don't. The sales of used goods are not included because they were produced in a previous year and are part of that year’s GDP.

The entire underground economy of services paid “under the table” and illegal sales should be counted—but is not—because it is impossible to track these sales. In a recent study by Friedrich Schneider of shadow economies, the underground economy in the United States was estimated to be 6.6% of GDP, or close to $2 trillion dollars in 2013 alone.

Transfer payments, such as payment by the government to individuals, are not included, because they do not represent production. Also, production of some goods—such as home production as when you make your breakfast—is not counted because these goods are not sold in the marketplace.

The concept of GDP may be fairly straightforward—it's just the dollar value of all final goods and services produced in the economy in a year—but actually calculating the more than $16 trillion-dollar US GDP is a full-time job for a brigade of government statisticians!

Government economists at the Bureau of Economic Analysis, BEA, within the US Department of Commerce, piece together estimates of GDP from a variety of sources.

Once every five years, in the second and seventh year of each decade, the Bureau of the Census carries out a detailed census of businesses throughout the United States. In between, the Census Bureau carries out a monthly survey of retail sales. These figures are adjusted with foreign trade data to account for exports that are produced in the United States and sold abroad and for imports that are produced abroad and sold here. Once every ten years, the Census Bureau conducts a comprehensive survey of housing and residential finance. Together, these sources provide the main basis for figuring out what is produced for consumers.

To determine investment, the Census Bureau carries out a monthly survey of construction and an annual survey of expenditures on physical capital equipment.

For what is purchased by the federal government, the statisticians rely on the US Department of the Treasury. An annual Census of Governments gathers information on state and local governments. Because a lot of government spending at all levels involves hiring people to provide services, a large portion of government spending is also tracked through payroll records collected by state governments and by the Social Security Administration.

With regard to foreign trade, the Census Bureau compiles a monthly record of all import and export documents. Additional surveys cover transportation and travel, and adjustment is made for financial services that are produced in the United States for foreign customers.

Many other sources contribute to the estimates of GDP. Information on energy comes from the US Department of Transportation and Department of Energy. Information on healthcare is collected by the Agency for Health Care Research and Quality. Surveys of landlords find out about rental income. The Department of Agriculture collects statistics on farming.

All of these bits and pieces of information arrive in different forms, at different time intervals. The BEA melds them together to produce estimates of GDP on a quarterly basis—every three months. These numbers are then annualized by multiplying by four. As more information comes in, these estimates are updated and revised. The advance estimate of GDP for a certain quarter is released one month after a quarter. The preliminary estimate comes out one month after that. The final estimate is published one month later, but it is not actually final. In July, roughly updated estimates for the previous calendar year are released. Then, once every five years, after the results of the latest detailed five-year business census have been processed, the BEA revises all of the past estimates of GDP according to the newest methods and data, going all the way back to 1929.

Summary

  • The size of a nation’s economy is commonly expressed as its gross domestic product, or GDP, which measures the value of the output of all goods and services produced within the country in a year.

  • GDP is measured by taking the quantities of all goods and services produced, multiplying them by their prices, and summing the total.

  • GDP can be measured either by the sum of what is purchased in the economy or by what is produced.

  • Demand can be divided into consumption, investment, government, exports, and imports. What is produced in the economy can be divided into durable goods, nondurable goods, services, structures, and inventories.

  • To avoid double counting—adding the value of output to the GDP more than once—GDP counts only final output of goods and services, not the production of intermediate goods or the value of labor in the chain of production.

  • The gap between exports and imports is called the trade balance. If a nation's imports exceed its exports, the nation is said to have a trade deficit. If a nation's exports exceed its imports, it is said to have a trade surplus.

Self-check questions

Country A has export sales of $20 billion, government purchases of $1,000 billion, business investment is $50 billion, imports are $40 billion, and consumption spending is $2,000 billion. What is the dollar value of GDP?

GDP=C + I + G + (X - M)GDP=$2,000billion+$50billion+$1,000billion+($20billion$40billion) GDP=$3,030billion

Which of the following are included in GDP, and which are not?

  • The cost of hospital stays
  • The rise in life expectancy over time
  • Child care provided by a licensed day care center
  • Child care provided by a grandmother
  • The sale of a used car
  • The sale of a new car
  • The greater variety of cheese available in supermarkets
  • The iron that goes into the steel that goes into a refrigerator bought by a consumer

Hospital stays are part of GDP. Changes in life expectancy are not market transactions and thus are not part of GDP. Child care that is paid for is part of GDP. If Grandma gets paid and reports this as income, it is part of GDP, otherwise it is not. A used car is not produced this year, so it is not part of GDP. A new car is part of GDP. Variety does not count in GDP, where the cheese could all be cheddar. The iron is not counted because it is an intermediate good.

Review questions

  • What are the main components of measuring GDP with what is demanded?

  • What are the main components of measuring GDP with what is produced?

  • Would you usually expect GDP as measured by what is demanded to be greater than GDP measured by what is supplied, or the reverse?

  • Why must double counting be avoided when measuring GDP?

Problem

Last year, a small nation with abundant forests cut down $200 worth of trees. $100 worth of trees were then turned into $150 worth of lumber. $100 worth of that lumber was used to produce $250 worth of bookshelves. Assuming the country produces no other outputs, and there are no other inputs used in the production of trees, lumber, and bookshelves, what is this nation's GDP?

In other words, what is the value of the final goods produced including trees, lumber and bookshelves?

Attribution

This article is a modified derivative of "Measuring the Size of the Economy: Gross Domestic Product" by OpenStaxCollege, CC BY 4.0.

The modified article is licensed under a CC BY-NC-SA 4.0 license.

References

U.S. Department of Commerce: Bureau of Economic Analysis. “National data: National Income and Product Accounts Tables.” http://bea.gov/iTable/iTable.cfm?ReqID=9&step=1.

U.S. Department of Commerce: United States Census Bureau. “Census of Governments: 2012 Census of Governments.” http://www.census.gov/govs/cog/.

United States Department of Transportation. “About DOT.” Last modified March 2, 2012. http://www.dot.gov/about.

U.S. Department of Energy. “Energy.gov.” http://energy.gov/.

U.S. Department of Health & Human Services. “Agency for Healthcare Research and Quality.” http://www.ahrq.gov/.

United States Department of Agriculture. “USDA.” http://www.usda.gov/wps/portal/usda/usdahome.

Schneider, Friedrich. Department of Economics. “Size and Development of the Shadow Economy of 31 European and 5 other OECD Countries from 2003 to 2013: A Further Decline.” Johannes Kepler University. Last modified April 5, 2013. http://www.econ.jku.at/members/Schneider/files/publications/2013/ShadEcEurope31_Jan2013.pdf.

Measuring the size of the economy: gross domestic product (article) | Khan Academy (2024)

FAQs

How does GDP measure the size of the economy? ›

GDP measures the monetary value of final goods and services—that is, those that are bought by the final user—produced in a country in a given period of time (say a quarter or a year). It counts all of the output generated within the borders of a country.

How do you calculate GDP questions and answers? ›

What is the GDP Formula?
  1. GDP = C + G + I + NX.
  2. C = consumption or all private consumer spending within a country's economy, including, durable goods, non-durable goods, and services.

What problem is solved by using real GDP? ›

By eliminating the distortion caused by inflation or deflation or by fluctuations in currency rates, real GDP gives economists a clearer idea of how the total national output of a country is growing or contracting from year to year.

Is GDP growth rate real or nominal? ›

The real GDP growth rate is a more useful measure than the nominal GDP growth rate because it considers the effect of inflation on economic data. The real economic growth rate is a "constant dollar" figure, avoiding the distortion from periods of extreme inflation or deflation to give a more consistent measure.

What is GDP a measure of quizlet? ›

GDP measures the value of total production, total income, and total expenditure. The value of the final goods and services produced in a given year expressed in terms of the prices of that same year.

What is GDP and how is it calculated? ›

The GDP calculation accounts for spending on both exports and imports. Thus, a country's GDP is the total of consumer spending (C), business investment (I), government spending (G), and net exports, which is total exports minus total imports (X – M). Gross national product (GNP) is a similar measure to GDP.

What is the simplest way to calculate GDP? ›

GDP Formula

GDP = private consumption + gross private investment + government investment + government spending + (exports – imports).

What are the three ways of measuring GDP? ›

Gross Domestic Product: How it is Measured
  • The Output Method (all value added by each producer),
  • The Income Method (all income generated) and.
  • The Expenditure Method (all spending).

What is the easiest way to explain GDP? ›

Gross domestic product (GDP) is the most common measure for the size of an economy, and it measures the value of total final output of goods and services produced by that economy in a certain period of time.

How to measure GDP growth rate? ›

To calculate the economic growth rate, the growth rate of a financial measure is calculated. Gross Domestic Product, GDP measures the economy's stability and progress. To measure its growth rate, divide the GDP of a later year by the GDP of a prior year and subtract 1.

Do higher taxes increase or reduce investment? ›

Measures of the magnitude of the investment and consumption changes vary, but the relationship between the variables is consistently negative: as tax levels or rates decrease, investment and/or consumption increases and vice versa.

Why is GDP a good measure of economic growth? ›

Gross domestic product tracks the health of a country's economy. It represents the value of all goods and services produced over a specific time period within a country's borders. Economists can use GDP to determine whether an economy is growing or experiencing a recession.

What is the difference between a recession and a depression? ›

'Recessions' vs. 'Depressions' in the Economy. A recession is a downtrend in the economy that can affect production and employment, and produce lower household income and spending. The effects of a depression are much more severe, characterized by widespread unemployment and major pauses in economic activity.

What is the rule of 70? ›

The Rule of 70 Formula

Hence, the doubling time is simply 70 divided by the constant annual growth rate. For instance, consider a quantity that grows consistently at 5% annually. According to the Rule of 70, it will take 14 years (70/5) for the quantity to double.

How to calculate real GDP per person? ›

Real GDP per capita is calculated by dividing GDP at constant prices by the population of a country or area. The data for real GDP are measured in constant US dollars to facilitate the calculation of country growth rates and aggregation of the country data.

Why is GDP an accepted way of measuring the economy? ›

Today, the predominance of GDP as a measure of economic growth is partly because it is easier to quantify the production of goods and services than a multi-dimensional index can measure other welfare achievements.

How is GDP growth calculated? ›

To calculate the economic growth rate, the growth rate of a financial measure is calculated. Gross Domestic Product, GDP measures the economy's stability and progress. To measure its growth rate, divide the GDP of a later year by the GDP of a prior year and subtract 1.

How does the size of a country's GDP affect the quality? ›

The size of a country's GDP serves as an indicator of the economic health of a country, as it encompasses the total value of goods and services produced. A larger GDP generally indicates more available goods and services, potentially leading to higher living standards.

Does country size affect GDP? ›

We finally provide estimates of the effect of country size on the 10-year average of GDP growth rates and this strongly confirms the main result that country size has a negative effect on GDP growth.

References

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