List includes metropolitan areas according only to the studies of ESPON, Eurostat, and OECD.
For this reason some metropolitan areas, like the Italian Genoa Metropolitan Area (with a population of 1,510,781 as of 2010[1]) or the Ukrainian Kryvyi Rih metropolitan area (with a population of 1,170,953 as of 2019[2]), are not included in this list, with data by other statistic survey institutes.
The concept of a functional urban area defines a metropolitan area as a core urban area defined morphologically on the basis of population density, plus the surrounding labour pool defined on the basis of commuting.
Figures in the first two population columns use a harmonised definition of a Functional urban area developed jointly in 2011, with delimitation basing on the DEGURBA method.
[3][4] Further information on how the areas are defined can be found in the source documents.