P1 to P10: the golf swing positions defined

What each of the ten numbers points at

P1, P4, P7, P10Numbers named by an event rather than a horizontal club or arm

Ten numbers cover one swing. P1 is address, the setup before anything moves. P2 is the frame where the shaft first reaches parallel to the ground going back. P3 is where the lead arm reaches parallel. P4 is the top, which Golf Insider UK defines as the club's furthest point before the change of direction.

Coming down, the two landmarks arrive in reverse. P5 is the lead arm parallel again, on the way down this time. P6 is the shaft parallel again, the last named frame before contact. P7 is impact, the clubface meeting the ball, and the only one of the ten the ball responds to.

Past the ball the pattern mirrors once more. P8 is the shaft parallel past impact, P9 is the trail arm parallel, and P10 is the finish. Notice the split. P1, P4, P7 and P10 name moments; the six between them are named by a club or an arm passing horizontal, which is what makes them the easiest to find on video.

Who numbered the swing

This did not come out of a laboratory. Golf Insider UK credits Mac O'Grady, the tour player turned teacher, with first popularising the ten positions. Writing for the United States Golf Teachers Federation in 2011, certified examiner David Hill traces Mike Bennett and Andy Plummer's Stack and Tilt back to Homer Kelley's The Golfing Machine and to O'Grady's teaching, and dates its arrival to the June 2007 cover of Golf Digest.

Bennett and Plummer's teaching is the reason a lesson today says P6 rather than shaft parallel coming down. What none of these sources points to is a founding document: no dated paper, no standards body, no committee. That is why two coaching sites can print different definitions of the same number and neither is breaking a rule.

Why the swing needed a shared vocabulary

Nine eventsFrames named across 92 reviewed biomechanics studies

A number is only comparable against the same number. If a coach says the lead wrist is cupped at the top and you send a clip, you both have to be stopped on the same frame or you are discussing two different pictures. That is the entire job the numbering does.

Biomechanics hit the same wall. A systematic review of golf swing kinematics screened 517 publications, included 92, and found all of them agreed on four phases, address, backswing, downswing and follow-through, subdivided by nine named events defined mostly by the club passing horizontal or vertical. Its own top of the backswing is the instant clubhead speed starts pointing downward and forward: computable, not visible. HackMotion calls the top the highest point of the backswing, which you can see. Neither definition guarantees the same frame.

Where two coaches disagree honestly

Put two published lists side by side and the edges do not line up. Golf Insider UK calls P5 the transition and pins it to the lead arm reaching parallel on the way down: one frame. HackMotion calls P5 the early downswing and has it running from the top until the club reaches parallel: a stretch of swing, not a frame.

P9 is the one that only sounds contested: one list calls it the trail arm parallel to the ground, the other the mirror of P3, and those are two ways of naming the same frame. Halfway back causes the most trouble, because HackMotion attaches it to P3 while plenty of coaches use it for the shaft-parallel frame at P2, and the review calls that same frame mid-backswing. Saying the landmark out loud costs three words and cannot be misread.

The frames a phone may not have

0.25–0.31 sDownswing duration for male golfers, 92-study review

How easy a position is to find depends on how fast that part of the swing is moving. The review's tables put the downswing at roughly 0.25 to 0.31 seconds for male golfers and 0.36 to 0.39 for female golfers, with a standard deviation under 0.04 seconds for the men.

Set that against a frame rate. At 30 frames per second a quarter-second downswing gives seven or eight frames between P4 and P7, so P5 and P6 get one frame each at best and impact often falls between two. The review found 55 of its 92 studies sampling between 100 and 300 frames per second, the distance between a lab and a phone. Pebble Swing reads joint angles out of the frames it has, and a frame your clip never recorded is not recoverable afterwards.

What a number does not claim

A P number names a moment. It does not prescribe a shape and it carries no verdict. Titleist Performance Institute states as much on its about page: it does not believe in one way to swing a club, but in an infinite number of styles, with one efficient way for each player, set by what that player can physically do.

Golf Insider UK closes with a line worth borrowing: forces move the golf ball, not positions. Two players can look a long way apart at P4 and have the club doing the same job by P7. The comparison that pays is with yourself, the same landmark filmed from the same spot, across enough swings to separate a habit from a frame the camera caught.