It is the world's most populous metropolitan area (35,327,000 at 2005 estimate[1]), covering an area of approximately 13,500 km² (5,200 mi²). It is the second largest in the world in terms of built-up or urban function landmass at 7,800 km² (3,000 mi²). Only the urban area surrounding New York City, at 8,700 km², is larger.

Like most metropolitan areas, the actual population size depends on definition. There are various different definitions used for what is commonly known as Greater Tokyo Area.