Usually the weight of the club head is increased by applying a lead tape on the head back or around the hosel. Alternatively, you can also add a lead or tungsten weight in the tip of the shaft. Reducing is not so easy and it could be done by drilling the head (usually back of the head) or by drilling the bottom of the hosel bore.
Changing the length of the shaft is in practice only useful for driver and woods. In iron sets the length differences between clubs are constant, typically 0.5 inch. Matching the MOI of the entire set of irons can in practice only be achieved by adjusting the weight of the individual heads.
The calculator computes the effective change in MOI of the entire club after applying the head weight and club length adjustments. The picture at the bottom of this page shows how to measure the distance of the center of gravity from the end of the club.
- Conversion to other MOI units are available here.
- The result of the calculation based on correct measurements is the good approximation, but it is still an approximation. Use it at your own risk.
update: October 2021