What is actual horsepower of this single phase ac motor
The horsepower of an induction motor can not be calculated from the current without knowing the motor efficiency and power factor. For single phase power, Hp = (V X I X eff. X pf) / 746. An online calculator that simply converts current and voltage to horsepower without taking that into consideration will not give a good answer. A tiny induction motor is likely to have a very low efficiency. The power factor is less than one, but perhaps not so low because of the extremely low efficiency.