Ban Khai (Thai: บ้านค่าย, pronounced [bâːn kʰâːj]) is a district (amphoe) in the central part of Rayong province, eastern Thailand.

In 1767 after Ayutthaya was destroyed by the Burmese, King Taksin the Great lead his troops to build a Siamese military base at Chanthaburi.

[1] Ban Khai was created as a district of Rayong Province in 1902.

Neighboring districts are (from the west clockwise) Nikhom Phatthana, Pluak Daeng, Wang Chan and Mueang Rayong.

The district is divided into seven sub-districts (tambons), which are further subdivided into 66 villages (mubans).