The Gini coefficient is a single number aimed at measuring the degree of inequality in a distribution.
The coefficient values range from 0 (or 0%) to 1 (or 100%), with 0 representing perfect equality and 1 representing perfect inequality.
It is most often used in economics to measure how far a country’s wealth or income distribution deviates from a totally equal distribution.
The graph shows that the Gini coefficient is equal to the area marked divided by the sum of the areas marked and , that is,
It is also equal to and to due to the fact that (since the axes scale from 0 to 1).