When will India overtake China in population?

[Tender Branson]

Ask me again after the 2020 Census in China and the 2021 Census in India.

It will definitely be after those years.

Also: should one include the populations of Taiwan, Hongkong and Macao in the overall Chinese numbers or not ? This makes a big difference - of 2 years.

[Tender Branson]

If we are not taking into account Taiwan, Hongkong and Macao as part of China, then the most likely answer is 2023.

China had 1395,4 million people at the end of 2018 (as per here) and went up by 5.3 million. That would yield some 1422 million people by the end of 2023.

India had 1211 million people during the (early) 2011 Census and is growing at a clip of 17-18 million people per year. That would also yield some 1420 to 1425 million people by the end of 2023.