There are around 8.2 billion people on Earth, and the number is still going up — by roughly 70 million a year, or about two people every second. The world passed 8 billion in November 2022. It took all of human history until about 1804 to reach the first billion, and only twelve years to add the most recent one. But the growth is slowing down, and demographers expect the total to peak this century and then start falling.
How Big Is a Billion?
A million seconds is about eleven and a half days. A billion seconds is nearly 32 years.
If you counted to 8.2 billion at one number a second, without sleeping, it would take about 260 years. If every person on Earth stood shoulder to shoulder, packed tightly, they would all fit inside an area roughly the size of Los Angeles — which sounds impossible until you realise how much space cities and farmland take up per person.
Written out, 8.2 billion is 8,200,000,000. In India that number would be written 820 crore, using a completely different grouping system.
The Growth Was Not Steady
For most of human history the population barely grew at all. Around 10,000 years ago, before farming, there may have been about five million people on the whole planet — fewer than live in Singapore today.
Farming allowed more people to be fed from the same land, and the number crept up to around 200 million by the year 1 CE and around 600 million by 1700. Then it took off.
The first billion arrived around 1804, the second in 1927, the third in 1960, the fourth in 1974, and after that roughly one every twelve or thirteen years. The cause was not people having more babies — it was people stopping dying, thanks to clean water, sewers, vaccines and better food.
Where Everyone Lives
Population is spread extremely unevenly. Asia holds around 60% of humanity on about 30% of the land. Africa holds around 18% and is growing fastest. Europe, the Americas and Oceania hold the rest.
India is the most populous country with over 1.4 billion people, having passed China in 2023. China is second, and the United States a distant third at around 340 million.
Draw a circle about 4,000 kilometres across centred on the South China Sea and it contains more people than the entire rest of the world put together. It takes in China, India, Japan, Indonesia, Bangladesh, the Philippines and several more, in about 6% of the Earth's surface.
Empty Places
Meanwhile, huge areas have almost nobody. Antarctica has no permanent residents at all. Greenland is 2.16 million square kilometres with around 56,000 people, which works out at about 0.03 people per square kilometre.
Mongolia is the least densely populated country with a proper population, at around two people per square kilometre. Canada, Australia, Namibia and Iceland are all similarly empty.
At the other end, Monaco has around 19,000 people per square kilometre. Singapore, Bahrain, Malta and Bangladesh are the most crowded countries of any size, and Bangladesh is the striking one — around 175 million people in an area smaller than the state of Iowa.
Try This: Map Your Class
Here is a way to make world population make sense. If your class had exactly 100 people and represented the whole world, this is roughly what it would look like.
About 60 would be from Asia, 18 from Africa, 9 from Europe, 8 from Latin America and the Caribbean, 5 from North America and less than 1 from Oceania. Around 17 would speak Chinese as a first language and about 5 would speak English.
Around 57 would live in a city. About 10 would have no electricity. Roughly 25 would be under 15 years old and about 10 would be over 65. Try drawing this as a chart — the shape of it explains most of the news you will ever read about the world.
Cities Took Over
In 1800, around 3% of people lived in cities. In 1950 it was 30%. In 2007 the world passed the halfway mark, and today it is about 57%. By 2050 it is expected to be around two thirds.
Tokyo is the largest metropolitan area with around 37 million people, followed by Delhi, Shanghai, Dhaka and São Paulo. There are now over 30 megacities — defined as urban areas with more than 10 million people — and most of them are in Asia and Africa.
Lagos in Nigeria is one of the fastest growing. It had around 300,000 people in 1950 and now has more than 20 million, and estimates for 2100 run considerably higher.
Why Growth Is Slowing
The number of babies born per woman worldwide has more than halved since 1960, from about five to around 2.2. That is close to the replacement rate of 2.1, the level at which a population stays the same size.
The reasons are consistent everywhere it has happened: girls staying in school longer, women working outside the home, children surviving so families do not need to have many, access to contraception, and cities where children cost more and help less than they do on a farm.
More than half the world's countries are now below replacement rate, including all of Europe, China, Japan, Brazil, Iran, Thailand and the United States. Population in those countries keeps rising for a while anyway, because of momentum — a lot of people are already of child-bearing age.
The Peak
The United Nations projects the world population peaking at around 10.3 billion in the mid-2080s and then beginning to decline. Some other researchers put the peak earlier and lower, around 9.7 billion in the 2060s.
Nearly all remaining growth will come from a small number of countries, most of them in sub-Saharan Africa. Nigeria, the Democratic Republic of the Congo, Ethiopia, Tanzania and Pakistan are projected to add the most.
Some countries are already shrinking. Japan's population has been falling since around 2010, and China's began falling in 2022. South Korea has the lowest fertility rate ever recorded for a country, at well under one child per woman.
How Anyone Knows Any of This
Almost every country counts its people, usually every ten years, in an exercise called a census. The oldest continuous one is Sweden's, running since 1749, and the United States has held one every decade since 1790 because its constitution requires it.
India's census is the largest peacetime administrative operation on Earth, employing around 2.7 million people to visit every household in the country. China's involves around seven million enumerators.
Between censuses, statisticians estimate. They track births, deaths and migration, and they use surveys and satellite imagery to fill in the gaps. Some countries have not run a full census in decades because of war or cost, so the global figure of 8.2 billion is a very good estimate rather than a headcount — the real number is probably within a percent or two either way.
Getting Older
Because people are having fewer children and living longer, the world's average age is rising fast. It was about 22 in 1970 and is now around 30.
The differences between places are extreme. The median age in Japan is around 49, in Italy around 48, in Nigeria around 18 and in Niger around 15. Half of Niger's population is a child.
An older population means fewer working-age people supporting more retired ones, which is why pensions and healthcare are political arguments in nearly every rich country. A very young population means enormous demand for schools and jobs, which is the challenge across much of Africa.
People Move
Population change is not only about births and deaths. Around 280 million people — roughly 3.6% of the world — live in a country they were not born in, and the number has risen steadily for decades.
Most move for work or to join family. A smaller share, around 120 million, have been forced from their homes by conflict, persecution or disaster, and about two-thirds of those stay inside their own country rather than crossing a border.
Migration reshapes both ends. Countries with falling birth rates increasingly depend on it to keep their working-age population steady — without it, Germany, Italy, Japan and Canada would all be shrinking faster than they are. And money sent home by migrants, called remittances, totals well over 600 billion dollars a year, which is more than all the world's foreign aid combined.
What It Means
More people means more demand for food, water, energy and space, and the pressure is not spread evenly. The average person in a rich country uses many times the resources of the average person in a poor one, so where population grows matters less than how people live.
Food production has kept up so far, largely because of the Green Revolution of the 1960s and 1970s, when new crop varieties and fertilisers roughly tripled yields in Asia and Latin America. The scientist most associated with it, Norman Borlaug, is often credited with saving hundreds of millions of lives.
The questions now are about water, soil, energy and climate rather than about sheer numbers. Understanding population is really about understanding those, and about a simple fact worth remembering: for the first time in human history, the number of people on Earth is going to stop growing during the lifetime of someone reading this. To keep exploring, see how many countries there are and read about Asia, where most of the people are.
