Gini Coefficient (Gini Index)
Definition
A measure of income inequality on a scale of 0 to 100. A score of 0 represents perfect equality (everyone earns the same), while 100 represents perfect inequality (one person earns everything).
Why It Matters
The Gini Index reveals how evenly income is distributed within a population. High inequality is associated with lower economic mobility, worse health outcomes, higher crime, and social instability.
How It's Measured
Calculated from the Lorenz curve, which plots the cumulative share of income against the cumulative share of the population. The Gini coefficient is the ratio of the area between the Lorenz curve and the line of perfect equality.
Current Value
US Gini: approximately 39.8; World range: 24 (Slovakia) to 63 (South Africa)
Related Ranking
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Frequently Asked Questions
A measure of income inequality on a scale of 0 to 100. A score of 0 represents perfect equality (everyone earns the same), while 100 represents perfect inequality (one person earns everything).
The Gini Index reveals how evenly income is distributed within a population. High inequality is associated with lower economic mobility, worse health outcomes, higher crime, and social instability.
Calculated from the Lorenz curve, which plots the cumulative share of income against the cumulative share of the population. The Gini coefficient is the ratio of the area between the Lorenz curve and the line of perfect equality.
this entity is one of the U.S. population demographics concepts that recurs across this site. The definition above is the technical answer; the paragraphs below add the practical context for how the concept connects to the the U.S. Census Bureau ACS and decennial files data behind every per-entity page on the site.
In the the U.S. Census Bureau ACS and decennial files data, this concept shapes one or more of the fields that drive the per-entity grades and rankings on this site. The methodology page describes which fields feed into which output; this glossary entry documents the underlying term.
Source: U.S. Census Bureau ACS, 2026.