There will be more Indians than Chinese by 2022 when both Asian giants will have 1.4 billion people each and India's population will grow at a faster pace, according to the UN.
A report from the UN Department of Economic and Social Affairs on Wednesday said that in seven years, "India's population is projected to continue growing for several decades to 1.5 billion in 2030 and 1.7 billion in 2050, while the population of China is expected to remain fairly constant until the 2030s, after which it is expected to slightly decrease".
A similar UN report two years ago had projected that the population of each of the two countries would reach 1.45 billion in 2028 when India's would start to grow at a faster pace than China's.
The report issued periodically to update population project and the latest is called "World Population Prospects: The 2015 Revision".
It projects world's population current population of 7.349 billion to grow by over a billion to 8.5 billion over the next 15 years and reach 9.725 billion by 2050.
India's bigger population initially gives it the economic advantage of a demographic dividend or benefit from the increased productivity of the youth, but it will also put a greater stress on the resources of India's area of 3.288 million sq kilometres compared to China's 9.597 million sq kilometres.
India will also have to rev up its economy to create jobs for millions more and, therefore, Prime Minister Narendra Modi's has set a target of creating 100 million jobs by 2022 and emphasising the manufacturing.
Although India's population will continue to grow, paradoxically the median age of Indians will increase because of the slowing fertility rate, eroding the demographic dividend. The median age now at 26.6 is expected to rise to 31.2 in 2030, to 37.3 in 2050 and 47 in 2100, the report said.
The fertility rate or the number of children born to a woman is currently 2.48 and is expected to go down to 2.34 by 2020, to 2.14 by 2030 and to 1.89 by 2050, according to the report.
Population experts consider a fertility rate of 2.2 children per woman as the replacement rate, that keeps the population constant over the long range.