Kaptai (Bengali: কাপ্তাই) is an upazila of Rangamati District in the Division of Chittagong, Bangladesh. The name of the Kaptai was derived from the Tripuri word "Kaptetoima". It is said that in the past, the river was wild and full of tropical flora and fauna. Large quantities and several varieties of canes could be found along the river bank that flows from the south, upper ridge. The river reaches its estuary at the Kainsa Khyong (Karnafuli River).

Notable landmarks are the Karnaphuli Hydroelectric Power Station, the only hydroelectric power plant of Bangladesh. The Kaptai Dam, built for this purpose on the Karnaphuli River, created the Kaptai Lake, the largest man-made dam in Bangladesh.

Kaptai is located at 22°30′00″N 92°13′00″E / 22.5000°N 92.2167°E / 22.5000; 92.2167. It has a total area 258.99 km. Kaptai upazila is bordered by Kawkhali and Rangamati Sadar upazilas to the north, Belaichhari upazila to the east, Bandarban district to the south and Chittagong district to the west.

As of the 2022 Bangladeshi census, Kaptai upazila had a population of 55,410. The ethnic population was 24,543 (44.29%), of which Marma were 15,844, Tanchangya 6,881 and Chakma 1,246.

• Kaptai lake
• Karnaphuli Paper Mills
• Kaptai National Park is situated at Rangamati. It was established in 1999 and its area is 5,464.78 hectares(13,498.0 Acres).
• Waggachara Tea Estate is situated on the bank of the Karnaphuli river.

UNO: Md. Mohi Uddin.

Kaptai Upazila is divided into five union parishads: Chandraghona, Chitmorom, Kaptai, Raikhali, and Waggya. The union parishads are subdivided into 10 mauzas and 144 villages.

• Upazilas of Bangladesh
• Districts of Bangladesh
• Divisions of Bangladesh

• Sifatul Quader Chowdhury (2012), "Karnafuli Hydropower Station", in Sirajul Islam and Ahmed A. Jamal (ed.), Banglapedia: National Encyclopedia of Bangladesh (Second ed.), Asiatic Society of Bangladesh
• Nuruddin Mahmood and M Abdul Hai (2012), "Kaptai Lake", in Sirajul Islam and Ahmed A. Jamal (ed.), Banglapedia: National Encyclopedia of Bangladesh (Second ed.), Asiatic Society of Bangladesh