Moment of Inertia (MOI)

1. Heel-to-Toe
2. Crown-to-Sole
3. Club Face to Trailing Edge 

While players may think of MOI as a singular number, it’s really a combination of measurements across three distinct planes:

With increased stability across each of these planes, the club transfers more energy into the ball, leading to ball speed preservation and reduced sidespin on off-center strikes.

A club with higher MOI will stay more stable through impact, preserving ball speed and reducing Gear Effect on off-center hits. However, while some may equate MOI to directly forgiveness, it is only one part of the equation. Stability words in tandem with design features like Bulge & Roll and Center of Gravity (CG) location to produce the full experience of forgiveness.

It’s also worth noting that excessive MOI reduce maximum distance. Higher inertia means more resistance to twisting and turning, slowing down clubhead speed as a result.

In golf club design, higher MOI is achieved by placing a larger amount of the club head’s discretionary weight towards the perimeter of the club head. The further this weight is located away from the club head’s center of gravity, the more resistant to twisting the club will be. Nearly all types of modern clubs feature some degree of perimeter weighting, but high-MOI design is most apparent in mallet-style putters and large-headed drivers.

However, in driver design (as noted in the video above) MOI is just one of several performance variables that club designers consider in their efforts to provide the best combination of distance off the tee, accuracy, consistency and forgiveness. As Titleist VP of Advance Research & Innovation, Dr. Alan Hocknell explains, MOI only comes into play on those shots that are struck more than .5 inches away from the center of the driver face. Because this only accounts for 20-25% of shots that golfers typically hit with the driver, it is not as important in the design hierarchy as other factors like CG position, face design and an aerodynamic head shape. These variables play a role in every shot you hit.

The bottom line? Think of MOI as an insurance policy against your worst misses.

To find the best balance of MOI, CG, Coefficient of Restitution (COR), and aerodynamics for specific player profiles, Titleist combines each of these performance features in several unique ways. By creating a range of model options, golfers can choose the best blend of performance attributes to fit their individual playing style.