Laundry drying machine (1) comprising a rotatable laundry drum (3) designed to rotate about an axis of rotation (6), an electric motor (9) which is mechanically connected with the rotatable laundry drum (3) for rotating said rotatable laundry drum (3) about its axis of rotation (6); hot-air generator means (11) configured to supply a heated airflow to the drum (3) during a drying cycle; and an electronic control system (16) configured to provide a sensed signal (S1) which is indicative of a torque that said electric motor (9) provides to the rotatable laundry drum (3); determine the value of a parameter (ΔS1, TIME) that is indicative of variation of the sensed signal (S1) in time, and estimate the laundry-load contained within said chamber (4) based on said determined value of said parameter (ΔS1, TIME).