New release of the World Income Inequality Database — new WIID version includes companion datasets to improve study of global inequality

The UNU-WIDER World Income Inequality Database ― widely known by its acronym WIID ― provides the most comprehensive set of income inequality statistics available. It presents detailed information on income inequality for developed, developing, and transition countries. The latest version of the WIID can be downloaded here.

The newest version builds on the May, 2020 release. It updates the WIID through 2019 to its current level with over 20,000 data points and 3,700 unique country-year observations.

It is also released alongside a WIID Companion for the first time. The WIID Companion offers a more user-friendly, curated set of inequality statistics. In the WIID Companion, most of the necessary data selection and adjustment needed to analyse, describe, or compare levels of inequality between countries or over time has already been taken care of by UNU-WIDER’s inequality and data experts. 

The WIID Companion reports annual country and global per capita income distributions at the percentile level. It also includes a set of measures that summarize the distribution, including relative and absolute inequality indices and various income share ratios. It consists of two datasets. The first is a country-level inequality dataset with that contains a single series per country tracking the net per capita income distribution. The second reports on global inequality.

Read more about the WIID Companion here.  

About the WIID

For more than 20 years, the WIID has been used for research on global inequality. It has been used to analyse inequality trends across countries and to study the relationships between inequality and, for example, economic growth and development, public sector expansion, political conflict, religiosity, etc.

Initially compiled in 1997–99 for the UNU-WIDER/UNDP project Rising income inequality and poverty reduction: Are they compatible? and published in September of 2000, the WIID is a major public good which contributes to understanding inequality and monitoring progress towards the achievement of reduced inequalities in line with Sustainable Development Goal 10.

Database composition
Observations by variable type   Number of observations
Total observations 20,792
Gini coefficients 20,709
MLD indices (GE0) 9,496
Theil indices (GE1) 11,014
Palma indices 16,070
Bottom 40 per cent income shares 16,022
Income distribution by quintile shares 16,017
Income distribution by decile shares 15,228


Time span Number of observations
Total observations 20,792
Before 1960 311
1960–69 710
1970–79 920
1980–89 1,652
1990–99 3,748
2000–09 6,352
2010–19 7,098
2020– 1