UNU-WIDER releases new version of the World Income Inequality Database

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 WIID has long been used for research on global inequality, to analyse inequality trends across countries and to study the relationships between inequality and, for example, economic growth, foreign direct investment, real exchange rates, institutional development, labour regulations, economic sanctions, public sector expansion, political conflict, religiosity, and skilled migration.

It was 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 newest version is part of the 2019–23 UNU-WIDER work programme on Transforming economies, states, and societies. It retains most concepts from the previous versions, with new variables for shares and ratios, such as the share of national income held by the bottom 40% or the Palmer ratio. It also corrects for inconsistencies and other issues found in earlier editions.

In WIID4, the observations are current to the year 2018 and cover 201 countries and more than 11,000 data points in total. There are now more than 3,600 unique country-year observations in the database.

About the database
Observations by variable type   Number of observations
Total observations 11,685
Gini coefficients 11,615
Income distribution by quintile shares 7,337
Income distribution by decile shares 6,578


Time span Number of observations
Total observations 11,685
Before 1960 313
1960–69 689
1970–79 849
1980–89 1,441
1990–99 2,624
2000–09 3,148
2010–18 2,621