Thailand has a population of approximately 72 million people as of 2025, making it the 20th most populous country in the world and the fourth most populous in Southeast Asia. That figure sits between the populations of the United Kingdom and France, packed into a country roughly the size of France or twice the size of Wyoming. Yet the more revealing story is not the headline number but the speed at which Thailand's demographics are changing.
How Many People Live in Thailand?
With around 72 million residents, Thailand accounts for roughly 0.9% of the global population. It ranks behind Indonesia, the Philippines, and Vietnam among Southeast Asian nations, but ahead of Myanmar and Malaysia. Population density averages about 140 people per square kilometre, though that figure is wildly uneven: the central plains around Bangkok are intensely crowded, while the mountainous north and parts of the deep south remain sparsely settled.
Thailand's population has more than tripled since the mid-20th century, when about 20 million people lived in the kingdom. That explosive growth has now come to a near halt, and the country stands at a demographic turning point that will define its coming decades. You can learn more in our thailand country guide.
A Dramatic Demographic Transition
Thailand's population is currently growing by only about 0.15% per year, one of the lowest rates in Asia and a figure that is effectively flat. This is extraordinary for a middle-income country. Most nations slow their population growth only after becoming wealthy, but Thailand achieved near-zero growth while still developing economically.
The reason lies largely in one of the most successful family planning campaigns in history. Beginning in the 1970s, activist Mechai Viravaidya led a nationwide effort that made contraception cheap, accessible, and socially normalised. The campaign was so closely associated with him that condoms became nicknamed "mechais" in Thai. The total fertility rate, which exceeded six children per woman in the 1960s, has since fallen to roughly 1.1 births per woman, far below the replacement level of 2.1 and comparable to Japan and South Korea.
As a result, demographers project that Thailand's population will peak around the end of the 2020s and then begin a long decline. Some forecasts suggest the population could fall toward 55 million by the year 2100.
An Aging Society
The flip side of low fertility is rapid aging. Thailand's median age is now around 40 years, among the highest in Southeast Asia and well above neighbours like the Philippines or Laos. The country is aging faster than almost any nation in history relative to its income level.
By 2040, an estimated one in four Thais will be over the age of 65, placing Thailand among the world's "super-aged" societies. This shift carries enormous implications: a shrinking workforce supporting a growing number of retirees, rising healthcare and pension costs, and concerns about whether economic growth can be sustained. Policymakers increasingly debate immigration, automation, and incentives for larger families as possible responses.
Where Thais Live: Cities and Regions
Thailand is dominated by a single primate city. Greater Bangkok is home to roughly 11 million people, meaning about one in six Thais lives in the capital metropolitan area. Bangkok is one of the world's great megacities and the unrivalled centre of Thai politics, finance, education, and culture, a concentration that creates a stark gap between the capital and the rest of the country.
Beyond Bangkok, other urban centres are far smaller. Chiang Mai, the cultural capital of the north, has roughly 1.2 million people in its metro area. The northeastern region known as Isan is the most populous rural region, with a strong distinct identity and its own Lao-related dialect, while the island of Phuket in the south is the largest tourist hub. Overall, Thailand is now more than half urban, a reversal from a generation ago when most Thais were rural rice farmers.
Ethnic and Religious Makeup
Thailand is relatively homogeneous by Southeast Asian standards. Ethnic Thais make up around 75% of the population, with Thai Chinese comprising roughly 14% and well integrated into the broader society. Smaller communities include Malays in the south, various hill tribes in the north, and Khmer speakers near the Cambodian border.
Religiously, the country is one of the most uniform on earth: about 95% of Thais practise Theravada Buddhism, which shapes daily life, festivals, and the visual landscape of temples nationwide. A Muslim minority of around 4%, concentrated in the southern provinces, forms the largest religious minority. Thai is the official language, written in its own distinctive script and spoken with notable regional dialects.
Frequently Asked Questions
Is Thailand's population growing or shrinking?
It is barely growing, at about 0.15% per year, and is expected to peak around the end of the 2020s before entering a long-term decline driven by very low birth rates.
What is the most populous city in Thailand?
Bangkok, by a huge margin. Its metropolitan area holds about 11 million people, roughly one-sixth of the entire national population.
Why is Thailand's birth rate so low?
A pioneering family planning campaign launched in the 1970s, combined with rising education, urbanisation, and the high cost of raising children, pushed fertility down to around 1.1 births per woman, far below replacement level.
How does Thailand's population compare to its neighbours?
At about 72 million, Thailand is the fourth most populous country in Southeast Asia, behind Indonesia, the Philippines, and Vietnam, but ahead of Myanmar and Malaysia.
