Chai Nat (, ) is one of the central provinces (changwat) of Thailand. Neighbouring provinces are (from north clockwise) Nakhon Sawan, Sing Buri, Suphan Buri, and Uthai Thani. The town of Chai Nat is 188 km north of Bangkok.
According to the Ayutthaya Testimonies, the provincial center of Chai Nat was founded by the Siamese monarch SurindrarÃÂja in the early 11th century. He renamed Ban Pran Nuea () as Phra Nakhon Chai Nat Buri () and designated it as the new capital of the region, thereby superseding Phraek Si Racha as the principal administrative center of the polity.
Chai Nat is on the flat river plain of central Thailand's Chao Phraya River valley. In the south of the province, the Chao Phraya Dam (formerly Chai Nat Dam) impounds the Chao Phraya River, both for flood control as well as to divert water into the country's largest irrigation system for the irrigation of rice paddies in the lower river valley. The dam, part of the Greater Chao Phraya Project, was finished in 1957 and was the first dam constructed in Thailand. The total forest area is or 2.6 percent of the provincial area.
Chai Nat was first established during the Ayutthaya period and was used as a successful base of operations for confronting the Burmese army. As the Burmese were defeated every time, the area earned the name Chai Nat, meaning 'place of victory'.
After World War II, when the Japanese had left, economic conditions were bad and food was in short supply. Chai Nat suffered this problem especially badly when bandits gathered in the countryside stealing cattle and inciting violence and crime.
The provincial seal shows a dhammachakka with a mountain in the background. It refers to the Dhammachak Buddha image housed in the hall of Wat Dhammamoen, built on the slope of a mountain.
The provincial tree is the bael fruit tree (Aegle marmelos), and the provincial flower is the Rainbow Shower tree (Cassia javanica). Bleeker's sheatfish (Phalacronotus bleekeri) is the provincial fish.
The slogan of the province is "Venerable Luang Pu Suk, renowned Chao Phraya Dam, famous bird park and tasty khao taengkwa pomelo."
Chai Nat is divided into eight districts (amphoes). The districts are further subdivided into 53 sub-districts (tambons) and 503 villages (mubans).
As of 26 November 2019 there are: one Chai Nat Provincial Administrative Organization - PAO (') and 39 municipal (thesaban) areas in the province. Chai Nat has town (thesaban mueang) status. Further 38 subdistrict municipalities (thesaban tambon). The non-municipal areas are administered by 20 Subdistrict Administrative Organizations - SAO (ongkan borihan suan tambon).
Apart from Chao Phraya Dam, Chai Nat also has various important places such as
Since 2003, United Nations Development Programme (UNDP) in Thailand has tracked progress on human development at sub-national level using the Human achievement index (HAI), a composite index covering all the eight key areas of human development. National Economic and Social Development Board (NESDB) has taken over this task since 2017.