Ball Speed is the speed at which the ball leaves the club face along its initial path. While club speed is important in producing ball speed, it is not considered a true “launch condition” because players with the same club speed can have very different ball speeds.
The degree to which club speed is converted to ball speed is called
Smash Factor, also referred to as Transfer Efficiency. Generally, on well struck shots using a driver, the ball speed will exceed club speed by a factor of 1.5. This is referred to as a 100% transfer efficiency, with higher and slower ball speeds being rated as more or less efficient.