• Demographia measured the world's largest cities by population according to urban area.
• Urban areas are linked by commuting flows and social and economic interactions.
• The urban area of Tokyo, Japan, is the world's largest city with a population of 37,732,000.

There are several ways to measure the population of the world's largest cities.

Demographia, an urban public policy and demographic analysis site, ranked the largest cities in the world by measuring the populations in urban areas as opposed to official city limits or metropolitan statistical areas.

As defined by Alex Blei, a program scholar at New York University's Stern Marron Institute Urban Expansion Project cited in Demographia's report, urban areas are contiguous, built-up areas that "function as an integrated economic unit, linked together by commuting flows, social and economic interactions."

Here are the top 20 largest cities in the world, with populations measured by urban area in 2022.