Gini Coefficient Calculator
Measure income inequality with the Gini coefficient from the income shares of the five population quintiles (bottom 20% to top 20%). Use it when comparing distribution across regions, countries, or demographic groups.
Last updated: September 2026
Formula below · 2 sources (fred.stlouisfed.org, Wikipedia) · Updated Sep 2026
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About this calculator
The Gini coefficient measures income or wealth inequality on a scale from 0 (everyone has the same income) to 1 (one person has everything). It is defined from the Lorenz curve, which plots the cumulative share of income against the cumulative share of the population, ranked from poorest to richest: Gini = 1 − 2 × (area under the Lorenz curve). This calculator builds the Lorenz curve from the income shares of the five quintiles and measures the area with the trapezoid rule: Gini = 1 − Σ 0.2 × (L(k−1) + L(k)), where L(k) is the cumulative income share of the bottom k quintiles (L(0) = 0, L(5) = 1). Shares are sorted from smallest to largest and rescaled to sum to 100%, so small rounding errors in published data do not matter. Because it ignores inequality inside each quintile, a quintile-based Gini is a lower bound — typically a few hundredths below the Gini computed from individual incomes — and it can never exceed 0.8. Economists, policymakers, and researchers use the Gini coefficient to track inequality over time, compare countries, and evaluate redistribution policies.
How to use
Enter the share of total income received by each fifth of households. The U.S. Census Bureau reports 2023 household money-income shares of about 3.1%, 8.3%, 14.1%, 22.6% and 51.9%. The cumulative shares are 0.031, 0.114, 0.255, 0.481 and 1.000. Area under the Lorenz curve = 0.2 × [(0 + 0.031) + (0.031 + 0.114) + (0.114 + 0.255) + (0.255 + 0.481) + (0.481 + 1.000)] = 0.2 × 2.762 = 0.5524. Gini = 1 − 0.5524 = 0.4476, or about 0.45. The Census Bureau's own Gini for 2023, computed from individual household incomes, is about 0.49, higher because the quintile method cannot see inequality within each fifth. Perfectly equal shares (20% each) give 0.
Frequently asked questions
What does a Gini coefficient of 0 vs 1 mean in practice?
A Gini coefficient of 0 represents perfect equality, where every person or household earns exactly the same income. A coefficient of 1 represents perfect inequality, where a single entity earns all the income and everyone else earns nothing. In reality, most countries fall between 0.25 and 0.65. Scandinavian nations typically score around 0.25–0.30, while highly unequal economies can exceed 0.55. These benchmarks help contextualize any value you calculate.
How is the Gini coefficient used to compare income inequality between countries?
Analysts plot each country's Gini coefficient on a standardized scale, allowing direct comparisons regardless of currency or population size. International organizations like the World Bank and OECD publish annual Gini estimates to track whether inequality is rising or falling. A higher Gini score generally correlates with weaker social mobility, higher poverty rates, and greater political instability. Comparing Gini values over multiple years for the same country reveals whether redistribution policies — such as progressive taxation or social transfers — are working. However, the Gini should always be paired with other indicators for a complete picture.
Why does the Gini coefficient not fully capture wealth inequality?
The Gini coefficient measures the relative distribution of income or wealth but ignores the absolute levels involved. Two countries can share the same Gini score yet have vastly different standards of living if their average incomes differ greatly. It also treats gains at different points of the distribution equally, so it can miss extreme concentration at the very top. Additionally, the index is sensitive to how income is defined — whether it includes capital gains, government transfers, or in-kind benefits can shift results significantly. Supplementing the Gini with metrics like the Palma ratio or income share of the top 1% provides a more complete inequality analysis.