India is overtaking China today as the world's most populous country — according to this projection

By Katie Marriner

A MarketWatch analysis of UN data shows that India's population hits 1,425,782,975 on Friday

India is overtaking China today as the most populated country in the world, according to a MarketWatch projection of data released by the United Nations that shows India's population hitting 1,425,782,975 on Friday, while China's will fall to 1,425,748,032.

China had been the world's most populous country since at least 1950, when the UN started releasing population data.

Today's projection is based on data that was released in July 2022 in the United Nations' World Population Prospects and a simple linear equation. The July 2022 report said only that India is projected to surpass China as the world's most populous country "sometime in 2023."

So why is today -- arguably -- the day?

The UN collected data on the population of more than 200 countries and areas with at least 1,000 people in the previous year. The data are collected from a variety of sources, depending on how a country assesses its own population. The UN's population projections are then made for January 1 and July 1 of each year.

As a result, the UN has projected that India's population on January 1, 2023 was 1,422,026,528 and will be 1,428,627,663 on July 1, 2023, an increase of over 6.6 million people. On January 1, 2023, China sat at No. 1 with a population of 1,425,849,288, but its population is projected to drop to 1,425,671,352 by July as China loses a total of almost 178,000 people.

Without any other information between those dates, MarketWatch has looked at the rate of change per day to land on an exact date India has a larger population than China. It's a crude, but widely accepted approach.

How can we pick an exact date to mark the occasion? The answer can be found by comparing the rate of change of the population of both countries. According to the UN data that shows the difference in population between January 1 and July 1, India is adding an average of about 36,470 people per day, while China's population is falling, albeit slowly, losing about 983 people per day.

Using the daily rate of change to make a projection, India is becoming the world's most populous nation today. A further breakdown of the data by hour for April 14, suggests the moment happened in the early hours of the day.

To be sure, MarketWatch is using just one approach for estimating the size of India's population. While statisticians who assess human populations often look at census data, surveys and different models, there is wide room for interpretation. In the end, the figures are estimates. Among experts, it's widely accepted that India is overtaking China as the world's most populous nation this year, but there is disagreement over exactly when this is occurring.

There is more agreement about why this is happening. For decades, China enforced a one-child policy among its people in an effort to control the population size. The policy ended in 2016, but the new policy did not result in a baby boom or a large increase in the birth rate. In China today, the number of deaths is greater than the number of births. On the other hand, India's population has soared due to its younger population, higher birth rate and improvements in infant mortality.

India's rising population

This chart shows the total daily population based on UN population projections

-Katie Marriner

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04-15-23 1345ET

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