Abstract: Provided are a washing machine and a method of calculating the amount of laundry. The washing machine includes a spin basket which has an inner space to put laundry therein and is rotatably mounted about a rotation shaft in a rotational direction by driving a motor and includes: a rotation time calculating unit which calculates a time period when the spin basket rotates once; a pulse torque generating unit which supplies a predetermined current or voltage to the motor during the time period when the spin basket rotates once and generates a pulse torque through an output shaft from the motor; an acceleration measuring unit which measures rotation acceleration of the output shaft of the motor according to the pulse torque generated from the motor; and a weight calculating unit which calculates the weight of the laundry put in the inner space of the spin basket by the rotation acceleration.