Remember, this is just a ball park figure for normal most case.
Some shaft have tip or butt weight will not be applied on this rule.
1/2" = 3 swing weight points
2 gr club head weight = 1 swing weight point
5 gr grip = 1 swing weight point
9 gr shaft weight differences = 1 swing weight point
4* flatter lie = increase 1 swing weight point
Joe