Stangl was born in 1908 in Altmünster, located in the Salzkammergut region of Austria. He was the son of a night-watchman and had such an emotionally distressing relationship with his father that he was deeply frightened by and hated the sight of the elder Stangl's Habsburg Dragoons uniform. Stangl claimed his father died of malnutrition in 1916. To help support his family, Franz learned to play the zither and earned money giving zither lessons. Stangl completed his public schooling in 1923.