What is Swing Plane in Golf?

Imagine a giant invisible disk leaning against your shoulder, tilted at the same angle as your club shaft when you address the ball. The path the shaft traces during a good golf swing should roughly stay on that disk from takeaway through impact to finish. That disk is your swing plane. It is set by your posture and the length of the club — a driver swings on a flatter, more horizontal plane; a wedge on a steeper, more vertical one.

A swing that goes back too vertical is called steep. A swing that goes back too horizontal is called flat. Both are problems because they force the body to make compensating moves on the way down to get the club back to a workable impact position. Steep backswings often produce over-the-top downswings and pulls or slices. Flat backswings often produce hooks and shanks.

On-plane is not the same as on-line. The club moves in a tilted circle around the body — at the top of the backswing the shaft will sit roughly parallel to the target line, and at impact it will be back on the original plane. If the shaft ever leaves that disk and then has to find its way back, you have a compensation problem.