Yes, Tokyo is a megacity. It actually exceeds the threshold by a wide margin. The United Nations defines a megacity as a city with 10 million or more inhabitants, and the Greater Tokyo Area is home to roughly 41 million people, making it the most populous metropolitan area on the planet.
How Tokyo Meets the Megacity Threshold
The 10-million mark set by the United Nations is the standard benchmark. Tokyo clears it several times over, no matter how you draw the boundaries. The city proper (Tokyo Metropolis) had a population of about 14.25 million as of May 2025. The Greater Tokyo Area, which includes Tokyo and parts of six surrounding prefectures, reached approximately 41 million residents as of 2024. Both figures comfortably qualify.
Tokyo’s Rank Among Global Megacities
The 2025 edition of the UN’s World Cities report ranks the Tokyo urban agglomeration third in the world, with roughly 33.4 million people. That figure uses the UN’s own geographic definition, which is slightly smaller than the full Greater Tokyo Area. Under the broader metropolitan count of 41 million, Tokyo sits at the very top of any global city ranking.
The cities that compete with Tokyo for the top spot depend on which boundaries you use. Dhaka and Delhi are in the same tier under certain definitions, but no other metropolitan area on Earth matches the Greater Tokyo Area’s 41-million figure.
What Makes Tokyo’s Scale Unusual
Population alone doesn’t capture how enormous Tokyo feels in practice. Its rail network offers the clearest illustration. The Tokyo subway system carries about 8.7 million passengers every day, and that accounts for only 22 percent of the region’s total daily rail traffic. Across the full Greater Tokyo Area, roughly 40 million rail trips happen each day. No other city comes close to that volume.
Economically, Tokyo punches well above its weight even relative to its size. The metropolitan area generated approximately $888 billion in GDP in 2022, representing about 21 percent of Japan’s entire national economy. Per capita GDP sat around $63,000. For context, a single city producing a fifth of a major industrialized nation’s output is extraordinary. Few megacities anywhere carry that kind of economic concentration.
Why the Population Numbers Vary
You’ll see different figures for Tokyo’s population depending on the source, and they’re all technically correct. The confusion comes from three overlapping geographic definitions.
- Tokyo Metropolis (city proper): About 14.25 million people. This is the core administrative unit, the area governed by the Tokyo Metropolitan Government.
- Tokyo urban agglomeration (UN definition): About 33.4 million. This is the continuous built-up area the UN uses for international comparisons.
- Greater Tokyo Area: About 41 million. This includes Tokyo plus portions of Saitama, Chiba, Kanagawa, Ibaraki, Tochigi, and Gunma prefectures. It’s the broadest and most commonly cited figure for the full metropolitan region.
All three numbers exceed 10 million, so Tokyo qualifies as a megacity under every reasonable definition. The variation matters mainly when you’re comparing Tokyo to other world cities, since different organizations use different boundaries.
Is Tokyo Growing or Shrinking?
Japan as a whole has been losing population since 2008 due to low birth rates and limited immigration. Tokyo has bucked that trend for years by attracting young workers from other parts of the country, but growth has slowed considerably. The UN projects very modest change for the Tokyo agglomeration through the 2030s, with the population essentially plateauing. Some smaller cities in Japan are losing residents quickly, while Tokyo remains a magnet, but even that pull is weakening as the national population continues to decline.
This makes Tokyo unusual among the world’s largest megacities. Most top-tier megacities in South and Southeast Asia are still growing rapidly. Tokyo’s challenge over the coming decades is less about managing growth and more about maintaining infrastructure and services for a slowly aging population at an already massive scale.