Bangkok, known in Thai as Krung Thep Maha Nakhon and colloquially as Krung Thep, is the capital and most populous city of the Kingdom of Thailand. The city occupies 1,568.7 square kilometres (605.7 sq mi) in the Chao Phraya River delta in central Thailand and has an estimated population of 9.1 million people as of 2024, 15.9% of the country's population. Over 18.1 million people live within the extended Bangkok metropolitan area as of the 2025 estimate, making Bangkok a megacity and an extreme primate city, dwarfing Thailand's other urban centres in both size and importance to the national economy.