All population figures for the world's largest urban areas are simply estimates. There's no way to know the exact population of such a large place. If you don't like this list, you can review other lists, based on different methodologies.
1. Tokyo, Japan - 35,197,000
2. Mexico City, Mexico -19,411,000
3. New York, United States - 18,718,000
4. Sao Paulo, Brazil - 18,333,000
5. Mumbai, India - 18,196,000
6. Delhi, India - 15,048,000
7. Shanghai, China - 14,503,000
8. Kolkata, India - 14,277,000
9. Jakarta, Indonesia - 13,215,000
10. Buenos Aires, Argentina - 12,550,000
11. Los Angeles, United States - 12,298,000
12. Karachi, Pakistan - 11,608,000
13. Rio de Janeiro, Brazil - 11,469,000
14. Osaka-Kobe, Japan - 11,268,000
15. Al-Qahirah (Cairo) - 11,128,000
16. Lagos, Nigeria - 10,886,000
17. Beijing, China - 10,717,000
18. Manila, Philippines - 10,686,000
19. Moskva (Moscow), Russia - 10,654,000
20. Paris, France - 9,820,000
21. Istanbul, Turkey - 9,712,000
22. Soul (Seoul), South Korea - 9,645,000
Source: United Nations Population Division - http://esa.un.org/unup
