The invention relates to a die for manufacturing a film by extrusion, comprising two blocks (100, 200) that define a flow duct (110) between one another, at least one (200) of the two blocks comprising a body (210) that has a deformable portion (220) for modifying the outlet opening of the die, characterized in that means (300) for subjecting the deformable portion to a force comprise at least one bearing part (310) that extends in a general direction (V) perpendicular to the direction (L) of flow at the die outlet and comprises a first end (312) bearing against the deformable portion (220), adjusting means (350, 380) in contact with the bearing part (310) modifying the position of this part.