A method and apparatus to determine and correct track spacing during self-servowriting on a rotating recording medium. The recording medium comprising a plurality of tracks, wherein each track comprises a plurality of sectors, and a transducer mounted on an actuator arm pivotally coupled to a voice coil motor (VCM). The actuator arm is positioned by a servo. The method comprising the steps of: servowriting the at least one of the plurality of sectors with a servo pattern consisting of recorded transitions. The servowriting is performed on one more tracks within the sectors where the number of tracks being servowritten is less than total number of tracks that fills the rotating medium. The transducer is positioned relative to the rotating recording medium to a preselected radial position over a previously servowritten area of the rotating recording medium that has one or more previously recorded transitions. Next, an angular acceleration is imposed on the actuator arm by applying a predetermined amount of current to the VCM. The measurement and correction of a spacing of the tracks in the previously servowritten area is performed by measuring the amplitudes of the previously recorded transitions at least one time during the passage of the sectors beneath the transducer, and if the calibratng of the spacing is outside a predetermined tolerance, then continuing servowriting new recorded transitions using said adjustment factor on tracks following said previously servowritten area. In one embodiment, the method includes measuring a VCM torque constant (K) by applying a current impulse for a predetermined time (t) and measuring the back Electromotive Force (EMF) generated from the VCM to determine the torque per unit for the current impulse for the predetermined time (t) and to determine the back Electronic Force (EMF) per unit of angular velocity of the actuator arm. After the torque constant is determined, an adjustment factor is computed based on the values of the torque constant (K), the current impulse for the period of time (t), and the back Electromotive Force (EMF)per unit of angular velocity of the actuator arm. This adjustment factor is used while servowriting now recorded transitions tacks following the previously servowritten area.