A method of calculating at least a component of ink drop velocity in an ink jet printer includes jetting at least one first ink drop from a printhead firing plane. It is detected when the first ink drop is a first predetermined distance away from a reference plane. A first time period between the jetting and the detecting of the first ink drop is measured. At least one second ink drop is jetted from the printhead firing plane. It is detected when the second ink drop is a second predetermined distance away from the reference plane. A second time period between the jetting and the detecting of the second ink drop is measured. A difference between the first predetermined distance and the second predetermined distance is divided by a difference between the first time period and the second time period.