Kuznets Curve

Updated on January 29, 2024
Article byWallstreetmojo Team
Reviewed byDheeraj Vaidya, CFA, FRM

What Is Kuznets Curve?

The Kuznets curve is a well-known economic theory that explains the relationship between economic growth and income inequality. The theory seeks to explain the pattern of income inequality occurring in a country undergoing economic expansion or industrialization.

Kuznets curve

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According to the Kuznets curve theory, as a country undergoes industrialization and economic development, there is typically a rise in income inequality in the initial stages of this process. However, after a certain point, the level of inequality starts decreasing, and eventually, it reaches a state of balance or equilibrium.

Key Takeaways

  • The Kuznets curve is an economic theory proposed by Simon Smith Kuznets in the 1950s to understand the impact of economic growth on income inequality.
  • This curve depicts an inverted U-shaped or mountain-shaped curve that shows the relationship between economic growth and per capita income.
  • Developed or rich countries typically have less income inequality than developing nations.
  • The Environmental Kuznets Curve (EKC) is a related theory that studies how a country’s development impacts the environment.

Kuznets Curve Explained

Kuznets curve is named after the economist Simon Kuznets, who proposed this theory in the 1950s based on his research on economic growth in the United States. According to Kuznets’ curve hypothesis, the shape of the graph is an inverted U-shape, representing the impact of economic development on inequality.

Initially, income inequality tends to increase as people begin to earn more, but it reaches its peak and starts to decline at a certain point. In the latter stage, further, development does not lead to more inequality but reduces it, resulting in an inverse U-curve for income inequality.

In 1955, Kuznets applied this theory to cross-national countries to understand it better. According to the Kuznets curve analysis, developed nations tend to have lower inequality. In contrast, a developing or emerging nation will have the highest inequality. Since these countries have not developed fully, upper-rich and middle-class groups are causing economic inequality.

The Kuznets curve theory has several implications for policymakers and economists. Firstly, it suggests that economic growth and development are necessary to alleviate poverty and improve living standards, but they may also result in increased income inequality in the short run. Secondly, it implies that economic policies should promote economic growth while mitigating the negative effects of inequality. Finally, it highlights the importance of measuring and monitoring income inequality levels in a country to understand the impact of economic policies and promote more equitable growth.

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Let us look at examples of the Kuznets curve for a better understanding:

Example #1

Suppose a government undergoes some reforms and changes in the country’s policy. Some include globalization, liberalization, and amendment in the monetary policies and fiscal policies. As a result, domestic companies started earning more due to exports. As a result, the citizens also saw an increase in their annual income.

According to Kuznets’s analysis, the economy of this country was going to take a leap forming a mountain-shaped graph. As the nation grew, the per capita income also rose. But, as a result, there were inequalities between the income groups. 

Example #2

According to 2022 research conducted by fellowships in IIT Madras, the Kuznets curve hypothesis in developing nations has yet to be true. Sabuj Kumar Mandal, head of the social science department, argued that rich countries do not cure environmental problems. Besides, the graph formed an inverted “N’ shaped curve. 


The Kuznets curve provides a useful framework for understanding the relationship between economic development and inequality, but it has criticisms that should be considered.

Let us look at some of the criticisms of the Kuznets curve to understand the concept better:

  • The Kuznets curve does not accurately depict the development of individual nations but instead focuses on a cross-sectional analysis of countries. In addition, the inverted U-shaped curve Simon Kuznets observed in Latin America disappears as the place of study changes. Therefore, the curve may not apply to all countries and regions.
  • The sudden economic rise of East Asian countries such as Japan, China, South Korea, and Singapore is another factor that challenges the Kuznets curve analysis. From 1965 to 1990, these countries experienced a significant economic boom, drastically reducing poverty levels. In addition, the increase in export and production levels led to lower inequality, contrary to what the Kuznets curve theory predicts.
  • The observations from the East Asia Miracle suggest that countries experiencing economic growth tend to distribute the benefits more evenly throughout the economy. This contradicts the Kuznets curve theory, which suggests that capital accumulation leads to a rise in inequality. Thus, the theory may not fully explain the relationship between economic development and inequality in all cases.

Environmental Kuznets Curve (EKC) Hypothesis

The Environmental Kuznets Curve (EKC) hypothesis extends the Kuznets curve theory, proposing a relationship between economic growth and environmental degradation. The EKC hypothesis suggests that environmental quality initially declines as a country undergoes economic development, but then it starts improving as the country reaches a certain level of economic growth. Some key points about the EKC hypothesis include:

  • The EKC hypothesis proposes an inverted U-shaped relationship between economic growth and environmental degradation. This means that environmental quality initially declines as a country becomes more industrialized and developed, but then it starts improving after a certain level of economic growth is reached.
  • The EKC hypothesis suggests that environmental degradation is a necessary evil in the early stages of economic development but that economic growth eventually leads to improvements in environmental quality. This idea is controversial, and some critics argue that environmental degradation is an unacceptable cost of economic growth.
  • The factors contributing to the EKC turning point can vary depending on the country and its economic and social context. However, factors that may contribute to this turning point include increased public awareness of environmental issues, technological innovations, and changes in policy and regulations.
  • The EKC hypothesis has been applied to various environmental issues, including air pollution, water quality, and biodiversity loss. While some evidence supports the EKC hypothesis in some cases, the relationship between economic growth and environmental quality is complex, and the EKC hypothesis has been criticized for oversimplifying this relationship.

In conclusion, the Environmental Kuznets Curve (EKC) hypothesis is an important extension of the Kuznets curve theory that proposes a relationship between economic growth and environmental degradation. While the EKC hypothesis is controversial and has been criticized by some, it remains a useful framework for understanding the complex relationship between economic growth and environmental quality.

Frequently Asked Questions (FAQs)

What is the Kuznets curve ratio?

The Kuznets curve ratio measures income inequality, which compares the income of the highest-earning group to the lowest-earning group in a population. It typically considers the top 20% of the upper-income groups or the lowest 40% of the least-earning groups.

What is augmented kuznet’s curve?

The augmented Kuznets curve is a modified version of the Kuznets curve that considers other factors such as education, technological development, globalization, economic growth, and income inequality to understand the relationship between these variables better. This modified curve helps to provide a more comprehensive understanding of the complex relationship between economic development, inequality, and other factors.

What are the limitations of the Kuznet curve?

The limitations of the Kuznets curve include its oversimplification of the relationship between economic growth and income inequality, its focus on income rather than other indicators of well-being, and its lack of consideration for the potential negative impacts of economic growth on the environment and society.

This article has been a guide to what is Kuznets Curve. We explain it with the environmental Kuznets curve hypothesis, its criticism, and examples. You may also find some useful articles here –

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