The amount of forearm rotation in your golf swing is the subject of much debate. Players including Raymond Floyd and Nancy Lopez used a lot of forearm rotation in their swings. The swings of modern players including Scotty Scheffler and Xander Schauffele possess a more passive forearm rotation. With active forearm rotation toe of the club will be pointing straight up at waist high in the backswing. In the follow through at waist high the toe of the club will again be pointing straight up. When swinging the club back and through notice how your right palm and the clubface remain parallel to each other. This movement demonstrates an active forearm rotation – 90 degrees clockwise in the backswing, and 180 degrees counterclockwise in the forward swing.
At waist high with passive forearm rotation the clubface will be parallel to your spine and the toe of the club will be pointing at 10:00 o’clock. In the follow through at waist high the clubface will be parallel to your spine and the toe of the club will be pointing at 2:00 o’clock. The clubface squares at impact through body rotation rather than independent arm rotation. With passive forearm rotation the left wrist will be flatter at the top of the swing. With active forearm rotation the left wrist will remain at the same angle it was at address.
As I mentioned earlier it isn’t a right and wrong, but rather a preference and there are great players using both methods. I would recommend experimenting with both type swings to see what works best for you.