Gini Coefficient Calculator — Income Inequality
Enter the income (or income share) received by each fifth of the population — from the poorest 20% to the richest — and the calculator plots the Lorenz curve, computes the Gini coefficient on a 0–1 scale, and shows the Palma ratio as a complementary inequality measure.
0 = perfect equality · 1 = extreme inequality
- 1
Total income
5 + 10 + 15 + 22 + 48 = 100Sum of all five quintile values — used to convert each to a share. - 2
Lorenz area (trapezoidal rule)
0.1 × (0.05 + 0.15 + 0.3 + 0.52 + … ) = 0.304Area under the Lorenz curve using five equal-width trapezoids (width = 0.2). - 3
Gini coefficient
1 − 2 × 0.304 = 0.392
How does this calculator work?
The Gini coefficient G = 1 − 2A, where A is the area under the Lorenz curve found by the trapezoidal rule from five quintile income shares. Enter Q1 (poorest 20%) through Q5 (richest 20%) in any proportional unit; typical high-income countries score 0.25–0.40, while values above 0.50 indicate high inequality.
Formula
How this is calculated
The Gini coefficient summarises income distribution as a single number between 0 (everyone earns equally) and 1 (one person earns everything). It measures the area between the Lorenz curve and the diagonal line of perfect equality, then doubles it. The Lorenz curve plots cumulative income share (Y-axis) against cumulative population share (X-axis); a perfectly equal distribution would follow the 45° diagonal, while real distributions bow below it.
The calculator takes five quintile incomes sorted from lowest to highest, converts them to cumulative income and population shares, and applies the trapezoidal rule to estimate the area A under the Lorenz curve: each trapezoid contributes 0.2 × (Yᵢ + Yᵢ₋₁)/2. The Gini coefficient G = 1 − 2A. Values for high-income countries typically fall between 0.25 and 0.40; values above 0.50 indicate high inequality (e.g. South Africa ≈ 0.63, 2020 World Bank data).
The Palma ratio — top-quintile share divided by bottom-two-quintile share — is shown as a complementary measure that some economists prefer because it focuses on the extremes. You can enter percentage shares that add to 100, or any proportional incomes in a consistent currency; the ratio between quintiles is all that matters.
Frequently asked questions
These are approximate income share percentages for a moderately unequal country (Gini ≈ 0.38). The bottom 20% earns 5% of total income while the top 20% earns 48%. You can replace them with any country's published quintile data, or with your own income survey figures.
Yes — the calculator normalises the values to shares internally, so you can enter any proportional amounts (average income per quintile in dollars, for example). The unit does not matter as long as you are consistent across all five fields.
The diagonal 45° line represents perfect equality — every 20% of the population earns exactly 20% of income. The curved line below it is your Lorenz curve. The larger the gap between them (the greater the bowing), the higher the Gini coefficient.
Also known as
TG we-Calculate Editorial Team. (2026). Gini Coefficient Calculator — Income Inequality [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/gini-coefficient-calculator
TG we-Calculate Editorial Team. "Gini Coefficient Calculator — Income Inequality." TG we-Calculate. 2026. https://we-calculate.com/calculator/gini-coefficient-calculator.
TG we-Calculate Editorial Team, "Gini Coefficient Calculator — Income Inequality," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/gini-coefficient-calculator
@misc{wecalculate_gini_coefficient_calculator, title = {Gini Coefficient Calculator — Income Inequality}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/gini-coefficient-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?