Located between latitudes 15° 45' north and 19° 25' north and longitudes 96° 10' east and 98° 28' east. Kayin State shares the border with Yamethin District, Shan State and Kayah State in the north, Toungoo, Thaton and Mawlamyine districts in the west, Ye Township in the south and Thailand in the east. The area of the State is 11,731 sq.miles.
Kayin State has a hot and humid climate because of the mountain ranges that lie in its backdrop and its location, which is near the sea, in the tropics. The temperature of the hottest month in eastern mountain regions never falls below 71.9° F. Lowlands in the west and south of the state are located in the tropical monsoon climate. The lowest annual rainfall in the region is 120 inches and the highest is 190 inches. The regions get most of the rain in summer.
Some of the rivers and creeks in Kayin State are flowing from south to north due to the location of mountains. The main rivers in the state are Thanlwin, Thaungyin and Attaran rivers.