Gini Coefficient Calculator
Inequality in a distribution on a 0-to-1 scale — the Gini coefficient, with the shares that show what it is actually measuring.
The Gini coefficient is twice the area between the Lorenz curve and the line of perfect equality.
How the gini coefficient calculator works
The Gini coefficient is twice the area between the Lorenz curve and the line of perfect equality. Computed directly, it is the mean absolute difference between every pair of values, divided by twice the mean.
Zero means everyone has the same; one means a single person has everything. Real national income Ginis run from about 0.24 to 0.63, and the number is far more legible next to the top-decile and bottom-decile shares, which the calculator gives.
Formula: G = Σᵢ Σⱼ |xᵢ − xⱼ| / (2 n² x̄)
Worked examples
| Inputs | Gini coefficient | Note |
|---|---|---|
| Five unequal values | 0.4 | Gini 0.40 |
| Perfect equality | 0 | Gini 0 |
| Near-total concentration | 0.9 | Gini 0.9 |
FAQFrequently asked questions
What does the Gini coefficient measure?
Inequality: 0 is perfect equality, 1 is one person holding everything.
What are typical national values?
Disposable-income Ginis run from about 0.24 in the Nordic countries to over 0.60 in the most unequal. Australia is near 0.32, the UK 0.35, the US 0.39.
What are its limitations?
Very different distributions can share a Gini. It is most sensitive to the middle and understates changes in the tails, which is where inequality debates usually are.
Should I use it outside income?
It applies to any non-negative quantity — market share, land holdings, citation counts, file sizes.
Why report the shares too?
Because "the top fifth holds 47%" is a claim anyone can check against their intuition, and "Gini 0.34" is not.
Where these figures come from
- NIST Digital Library of Mathematical Functions — reference definitions for elementary and special functions
- Wolfram MathWorld — definitions and formulas for every topic on this page
- NIST/SEMATECH e-Handbook of Statistical Methods — the statistical formulas (mean, variance, z, confidence intervals, sample size)
- National curriculum in England — Mathematics — the terms and methods taught in UK schools
Last checked: September 2026. Formulas are fixed by mathematics and do not change with tax years or regulations.