A method for determining and varying the capacity, track per inch and bit per inch values of a hard disk drive. The method includes determining an optimal track per inch value for each head of the drive. The method then determines whether each head does not exceed a threshold BER value. If one or more heads do not exceed the threshold BER value then the BPI (data rates) of the non-performing heads are decreased until an acceptable BER is achieved. The BPI of performing heads may be increased to insure that the capacity of the disk drive still meets a target value. Likewise, if all of the heads are above the threshold value, the BPI of one or more of the performing heads may be decreased to improve the BER of the heads. The reduction in BPI is limited so that the drive always meets the target capacity value. The BPI and TPI values are stored in memory for use during the operation of the drive.