Kulachi is a city and the headquarters of Kulachi Tehsil (an administrative subdivision) of Dera Ismail Khan District in Khyber Pakhtunkhwa, Pakistan. It is situated 50 km from Dera Ismail Khan in the Damaan valley of the Sulaiman Range, and lies on the banks of the Gomal River (local name "Luni" or "Khuarha"), a tributary of the Indus River.