Gini Coefficient Calculator
Calculate the Gini coefficient to measure income or wealth inequality.
Enter income shares by group to compute the Gini index and plot the Lorenz curve.
What Is the Gini Coefficient? The Gini coefficient (or Gini index) is a statistical measure of inequality developed by Italian statistician Corrado Gini in 1912. It is the most widely used measure of income and wealth inequality worldwide. Values range from 0 to 1, where 0 represents perfect equality (everyone has the same income) and 1 represents perfect inequality (one person has everything).
The Lorenz Curve The Gini coefficient is derived from the Lorenz curve — a graph that plots cumulative income share against cumulative population share. If income were perfectly equal, the Lorenz curve would be a straight diagonal line (the line of perfect equality). The further the actual Lorenz curve bows below this line, the greater the inequality.
Calculating the Gini Coefficient For grouped data (e.g., income quintiles or deciles), the Gini coefficient is calculated as:
Gini = 1 - sum of (X_i - X_{i-1}) x (Y_i + Y_{i-1})
Where X represents the cumulative population share and Y represents the cumulative income share. This is the trapezoidal approximation of the area under the Lorenz curve.
Alternatively: Gini = A / (A + B), where A is the area between the line of equality and the Lorenz curve, and B is the area under the Lorenz curve.
How to Enter Data Enter the income shares of groups from poorest to richest, separated by commas. The shares do not need to sum to 100 — they will be normalized automatically. For example, entering “10,15,20,25,30” represents five equal-sized groups (quintiles) where the bottom 20% earns 10% of income and the top 20% earns 30%.
Interpreting the Result 0.00 - 0.20: Very low inequality (Nordic countries score around 0.25-0.30 after taxes) 0.20 - 0.35: Moderate inequality (most developed economies) 0.35 - 0.50: High inequality (many emerging economies) 0.50 - 1.00: Very high inequality (some developing nations exceed 0.60)
Real-World Examples As of recent data: Slovakia and Slovenia have Gini coefficients around 0.24 (low inequality). The United States is around 0.39. Brazil and South Africa are among the highest at 0.48-0.63. Global wealth inequality (not just income) is even more extreme, with estimates around 0.85.
Limitations The Gini coefficient summarizes inequality in a single number, which means different distributions can produce the same Gini. It is also sensitive to the middle of the distribution and less sensitive to changes at the extremes. Analysts often use the Gini alongside other measures such as the Palma ratio (top 10% / bottom 40%) for a fuller picture.