Bangkok is the capital and by far the largest city of Thailand, spread across 1,568.7 square kilometres of the Chao Phraya River delta about 25 kilometres upstream from the Gulf of Thailand. The 2010 census counted 8,305,218 people inside the city limits, and official estimates put the figure at about 10.5 million by 2020; the wider Bangkok Metropolitan Region held some 17.4 million in 2021, roughly a quarter of the country. Thais call it Krung Thep Maha Nakhon, the short form of a ceremonial name that Guinness lists as the world’s longest place name at 168 letters. What defines Bangkok is imbalance: it is one of the most extreme primate cities on Earth, dwarfing every other Thai town, and it sits on land that averages only 1.5 metres above sea level. The clearest way to understand it is to measure it against things, so this guide sets the capital beside its river, its rivals, its climate and the capitals Thailand has considered building instead.
1,568.7 km² of Delta Clay, 1.5 Metres Above the Sea
On paper Bangkok is a mid-sized province. Its 1,568.7 square kilometres rank only 69th among Thailand’s provinces, and only about 700 square kilometres of that is built up. The rest includes rice paddies and orchards on the eastern and western fringes, which exist mainly as flood detention basins. The urban sprawl has long since overflowed the boundary into six neighbouring provinces, which clockwise from the northwest are Nonthaburi, Pathum Thani, Chachoengsao, Samut Prakan, Samut Sakhon and Nakhon Pathom.
Height is where Bangkok is most unusual. The city stands on a layer of soft marine sediment known as Bangkok clay, averaging 15 metres thick, laid over an aquifer system of eight known units. Heavy groundwater pumping made the ground sink: by 1981 subsidence reached 120 millimetres a year. Controls on pumping cut the rate to 10 to 30 millimetres a year by the early 2000s, but parts of the city are now about a metre below sea level. The same clay amplifies distant earthquakes, so tower occupants have felt tremors centred hundreds of kilometres away in northern Thailand and Myanmar; seismic rules entered the building code only in 2007.
The only “hill” in the metropolitan area is man-made by accident. Phu Khao Thong at Wat Saket began as a giant chedi ordered by King Rama III; the soft ground could not bear it, the structure collapsed, and over decades the abandoned mound of brick and mud grew weeds until locals called it a mountain. The nearest real range, the Khao Khiao Massif, lies about 40 kilometres to the southeast. Floods follow from this flatness: severe inundations struck in 1995 and in 2011, when most of the northern, eastern and western districts were under water, some of them for more than two months. The river that shapes all of this is traced from source to sea in our guide to the Chao Phraya.
8.3 Million Against Chiang Mai’s 1.2 Million
When the British envoy John Crawfurd visited in 1822, he put Bangkok’s population at no more than 50,000. Growth quickened with Western medicine in the late 19th century and again after antibiotics arrived in the 1930s, and in the 1960s alone the city rose from about 1.8 million to 3 million people as migrants poured in from the provinces. By 1980 Bangkok was fifty-one times the size of Hat Yai and Songkhla, then the second-largest urban centre, which made it the most pronounced primate city in the world.
The gap is still enormous. Chiang Mai, founded in 1296 as the capital of the Lan Na kingdom and lying about 700 kilometres to the north, is usually called Thailand’s second city, yet its municipality holds only about 127,000 people and its whole urban area about 1.2 million. The most populous city municipality outside Bangkok is Nonthaburi, with 254,375 registered residents in 2019, and it is effectively a Bangkok suburb served by the MRT Purple and Pink Lines.
Money and services concentrate the same way. In 2022 the city produced 5.747 trillion baht of output, about US$164 billion, or 634,109 baht per person, more than twice the national average, and it alone accounts for 48.4 per cent of Thailand’s service sector. In 2000 Bangkok had 39.6 per cent of the country’s doctors, a ratio of one physician to 794 residents when the median province managed one to 5,667. The five oldest universities, Chulalongkorn, Thammasat, Kasetsart, Mahidol and Silpakorn, were all founded here between 1917 and 1943. Yet it is also a city of migrants: roughly half of the people counted there come from other provinces.
Thonburi Bank Against Rattanakosin Island
Bangkok is two cities that were joined on paper only in 1971, when Phra Nakhon province on the east bank merged with Thonburi province on the west; the Bangkok Metropolitan Administration took its current form the following year. The west bank came first. After the Burmese sacked Ayutthaya in 1767, King Taksin made the riverside customs town of Thonburi his capital. In 1782 his successor Rama I moved across the water to Rattanakosin Island, and the City Pillar raised there on 21 April 1782 marks the official founding of Bangkok as capital.
The two banks remain lopsided. Of the city’s fifty districts, thirty-five lie east of the Chao Phraya and only fifteen on the Thonburi side, which has fewer high-rises and more residential and semi-rural land. The east bank holds the Grand Palace, the government quarter along Ratchadamnoen Avenue, the Si Lom and Sathon towers and the malls of Siam and Ratchaprasong. Eleven bridges link the halves. Even the city’s name belongs to the west bank: one theory derives it from Bang Makok, a village named after an olive-like fruit, and Wat Arun on the Thonburi shore was once called Wat Makok. For the kingdom Bangkok replaced, see our page on the ruins of Ayutthaya.
193 Hot Days in 1960, 276 in 2018
Bangkok has a tropical savanna climate under the Köppen scheme, with three seasons: hot, rainy and cool. The annual mean is 28.9 °C. April is the hottest month, with an average high of 35.7 °C, and December the mildest, with an average low of 23.2 °C, so the “cool” season is cool only by comparison. The southwest monsoon arrives around mid-May and September is the wettest month, averaging 335.9 millimetres of rain, before the dry northeast monsoon takes over from October to February. The record high is 41.0 °C, set on 7 May 2023; the record low is 9.9 °C, in January 1955.
Concrete adds its own heat. The urban heat island has been measured at 2.5 °C above the surroundings by day and 8.0 °C by night. A climate impact group at NASA’s Goddard Institute for Space Studies counted how often the thermometer reaches 32 °C, and the trend is steep.
3.3 Square Metres of Green per Resident, 8 Per Cent Road
Space is the other scarce resource. Recent figures give Bangkok about 3.3 square metres of green space per person, against an average of 39 square metres in other Asian cities, roughly a tenth of the regional norm. One of the largest parks, the centrally located Lumphini, covers 57.6 hectares and connects by a 1.3-kilometre elevated walkway to Benjakitti Park. The Green Bangkok 2030 project aims for 10 square metres per person.
Roads cover about 8 per cent of the city’s surface, compared with 20 to 30 per cent in most Western cities, and there is no grid: forty-eight major roads feed a maze of sois, or lanes. In 2006 the city had 3,943,211 vehicles in use, 37.6 per cent of them private cars and 32.9 per cent motorcycles. The response has been to go up and under. The BTS Skytrain opened in 1999, the underground MRT followed, and the network now counts ten urban rail lines, three of them the BTS Light Green, Dark Green and Gold Lines. Suvarnabhumi Airport, opened in 2006, handled 52.8 million passengers in 2015, well past its designed capacity of 45 million.
Water was the original transport network. Until the late 19th century most residents lived on or beside the canals, earning Bangkok the nickname “Venice of the East”, and Charoen Krung, completed in 1864, was the first road built with Western techniques. The canals survive as drains and commuter routes: in 2023 the Chao Phraya Express Boat carried an average of 19,834 passengers a day across thirty-four stops, while the smaller Khlong Saen Saep service carried 28,801 a day across twenty-seven. By visitor numbers, meanwhile, Bangkok has repeatedly ranked first in the world; Euromonitor International counted a record 32.4 million visitors in 2024.
Phetchabun, Nakhon Nayok, Chachoengsao: Capitals That Were Never Built
Subsidence, floods and congestion have pushed Thai governments to ask whether the capital should stay. During the Second World War, Prime Minister Plaek Phibunsongkhram planned to move it to Phetchabun, and the plan failed. In the 2000s the Thaksin Shinawatra government asked the national planning council to draw up a move to Nakhon Nayok. The 2011 floods revived the idea, and in 2017 the military government commissioned a study of shifting government offices to Chachoengsao, east of the city. None has happened, which sets Bangkok apart from its neighbour Indonesia, where Jakarta’s role is being handed to the new city of Nusantara on Borneo.
The comparison says a great deal. Bangkok holds every branch of the national government, including the Government House, the Sappaya-Sapasathan parliament building and the Supreme, Administrative and Constitutional Courts, along with the Grand Palace and the headquarters of every major Thai bank. Moving all of that would mean unwinding two and a half centuries of concentration. For now the capital stays on its clay, protected by flood barriers, pumps and drainage tunnels, and hotter every decade. For the country-wide picture of heat and monsoon that frames the city, see our overview of the climate of Thailand.
Quick Facts About Bangkok
- Country: Thailand
- Continent: Asia (Southeast Asia)
- Country population: approximately 71.6 million
- Capital city status: Bangkok is the capital of Thailand, the seat of national government, and the location of foreign embassies, parliament, and the head of state's official residence.
Frequently Asked Questions
What is the capital of Thailand?
The capital of Thailand is Bangkok. Bangkok is the seat of national government, hosts most foreign embassies and consulates, and is typically where the head of state and parliament are located.
What continent is Bangkok in?
Bangkok, the capital of Thailand, is located in Asia, in the Southeast Asia region. As Thailand's capital, Bangkok serves as the country's primary connection to the broader Asian political, economic, and cultural sphere.
Why is Bangkok the capital of Thailand?
Bangkok was chosen as the capital of Thailand for reasons that typically combine geography, history, and politics. Capital city selections often reflect a desire for centrality (being accessible from across the country), historical importance (being a longstanding seat of government or culture), or neutrality (being acceptable to multiple regions or ethnic groups within the country). The specific reasons for Bangkok's designation are detailed in the city's history above.
What is Bangkok known for?
As the capital of Thailand, Bangkok is best known for housing the country's central government institutions — parliament, presidential or royal residences, supreme court, and key ministries. It is also typically a major cultural and economic center within Thailand, hosting national museums, embassies, and signature monuments. The introduction and history sections above provide detailed coverage of the city's specific notable institutions and landmarks.
Related Pages
- Thailand Country Guide — full geography, climate, economy, and culture overview
- Flag of Thailand — meaning, history, and design of Thailand's national flag