How we measure your swing
No black box. This page explains what the engine compares you against, exactly what it measures, and what a single phone camera honestly can't see, which we'd rather name than paper over.
What you're compared against
One thing: the model. It's a single set of numbers. Eight measurements at each of the nine swing positions, P1 (address) through P9 (finish). Written down by our founder and built on the legends of the game, the positions the game's greatest ball strikers share. Hitting an iron.
Be clear about what that is and isn't. It is one model swing, built the way our founder teaches, not an average of the field, not a survey of the tour, not a statistical band. Where it disagrees with a broad average of the field, the model wins, because the model is what we teach. Your report shows your number and the model's number side by side and lets you see the gap yourself.
The numbers describe an iron swing. That's our working assumption about the club in the founder's source frames rather than something stamped on them, and it's flagged as an assumption in the code until he confirms it. A model set for the driver is on the roadmap; today a driver is judged against a bigger pivot on top of this same baseline.
The eight measurements
We track 33 points on your body in every frame of your video, using Google's BlazePose model. Shoulders, elbows, wrists, hips, knees, ankles, head. From those points the engine finds your nine swing positions and reads the model's eight metrics. These are the founder's definitions, in his words:
Shoulder Turn. How much the shoulders turn. Zero is both shoulders parallel to the target line; going back reads closed, through the ball reads open. Measured at all nine positions.
Hip Turn. The same measurement, taken at the hips. Measured at all nine positions.
Shoulder Tilt. The relationship between your left and right shoulder. Zero is a shoulder line parallel to the ground. Measured on face-on video.
Hip Tilt. The difference between your right and left hip. Zero is a hip line parallel to the ground. Measured on face-on video.
Spine Angle Tilt. How much the spine is bent over from the waist. Measured down-the-line at P1 and P6 only. See the limits below.
Shoulder Drift. How far the shoulders move closer to or further from the target, measured at the middle of the back between the shoulder blades. Measured on face-on video from P2 on. P1 is the zero point.
Hip Drift. How far the hips move towards or away from the target, measured at the tailbone. Measured on face-on video from P2 on. P1 is the zero point.
Hip Bend. How much the hips are bent over at the ball. NOT measured. See below.
Turns and tilts are read in degrees; the two drifts are read in inches. Rotation is measured against your own address line, so the numbers never depend on how the camera was aimed. On top of the nine positions the engine reads continuous curves. Shoulder and hip rotation across the whole swing, weight shift, tempo. So a fault between positions doesn't slip through.
Seven of the eight, and what we can't see
Kinetic works from a single phone camera. Seven of the model's eight metrics survive that honestly. One does not, and two other things people expect us to measure don't either. Rather than fill the gaps with numbers that look right, we leave them blank and tell you why:
The pose model has no pelvis landmark. No sacrum, no tailbone. Without one, pelvis bend cannot be separated from spine bend on a 2D image. We could ship a plausible-looking proxy number; it would be a fake, so the metric stays blank instead.
At P1 and P6 your torso is roughly square to the camera and the reading is honest. At the turned positions, like the top of the backswing, a 2D image mixes your turn into what looks like bend. The model reads 2° back at the top; any flat projection of an 88°-turned torso reads roughly 38° forward. That is the projection lying, not you, so those positions go unscored.
We track the clubhead’s position, not which way the face points. The founder’s P6 face-vs-spine check is taught in your report as a rule to look for, and is never scored as a number.
The drift numbers rest on an assumption. Here it is. Shoulder Drift and Hip Drift are reported in inches, but a camera has no idea how big you are. To turn pixels into inches we assume every golfer's shoulders are 16 inches across (shoulder-joint to shoulder-joint), which is close to an adult male average. If your shoulders are wider or narrower than that, every inch value in your report is stretched or squeezed by the same proportion. Roughly 10 to 15 percent out for a typical golfer. It is consistent for you week to week, which is what makes it useful for tracking, but do not read it as a tape measure. When your profile carries a real measurement, we'll use that instead.
Per-metric confidence flags. Every number is checked against the visibility of the exact body points used to compute it. If a hip is hidden at the top or your ankles are out of frame, that metric, and only that metric, is tagged “low camera confidence” or dropped from your report entirely. A missing row is deliberate.
Angles are estimates. Every angle comes off a 2D image, so treat the report as a consistent yardstick for YOUR progress against the same model every week, not lab-grade 3D motion capture. We'd rather say that here than let a decimal point imply precision we don't have, which is why your report rounds to whole numbers.
No ball data from video. A camera on your body can't measure face angle or spin. If you have a launch monitor (Garmin R10, TrackMan, Golfzon and more), Kinetic imports those sessions and uses the real numbers instead of guessing.
One honesty rule matters more than any formula: a fault is only flagged when the measurement actually sees that fault. We removed several plausible-sounding fault detectors (casting, scooping, deceleration) because the 2D proxies behind them couldn't truly see them. A confidently wrong diagnosis is worse than silence.
What each camera angle can see
Where you stand the phone decides what we can measure. Motion toward the target runs across a face-on frame and disappears edge-on from behind, and motion toward the ball does the opposite. That is why we ask which view you filmed, and why the same swing filmed from the other side gives you a different half of the picture. Here is what each view gives you, so you know before you film rather than after.
Filmed from behind you, camera on the ball-to-target line, looking down it.
how the shaft sits against your plane line on the way back
whether your hands and the club stay inside your own swing plane
where your hands finish at the top, and whether they are stuck behind you
how far your elbows have come apart at the top
whether your elbows come back together into the ball
whether your trail elbow comes back in front of your trail hip at impact
whether you hold your posture or stand out of the shot coming down
how far your head moves off its starting spot
From this view we also read shoulder tilt, spine angle and hip tilt against the model at every position.
What this view cannot see. shoulders closed at p5, stance width, spine tilt at address, leg lines and takeaway width. Film the other angle and we will check those too.
Filmed from in front of you, camera square to your chest, looking at you.
whether your shoulders stay closed into the downswing or fire open early
how wide you set up to the ball
how your upper body is stacked over your lower body at address
whether your legs stay inside their own lines instead of sliding
how wide your takeaway stays before the arms fold
how far your head moves off its starting spot
From this view we also read shoulder tilt, shoulder drift, hip tilt and hip drift against the model at every position.
What this view cannot see. shaft plane (p2–p4), swing plane, hands at the top (p4), elbows apart at the top (p4), elbows separating (p5), reconnection (trail elbow at impact) and posture line. Film the other angle and we will check those too.
Nothing on this page is a marketing list. It is generated from the same table the engine gates on, so if a measurement moves views the words here move with it. When your report leaves something out, it says so and names the view that would show it.
The reference lines
Numbers aren't the whole method. On every face-on video the engine draws the same lines our founder draws on a lesson tee, anchored to your address frame, and then watches you against them:
A line from each ankle to its hip, carried on a little past the hip. They're the fence your lower body works between: at the top your lead hip should still be on its line, and coming down it should be past it.
The head box. One line just above your head and one just in front of it, sized from your own head. Your head should stay inside the box: dropping under the top line or pushing past the front line is the move behind most of what golfers call “casting” or “coming over the top”.
The lines scale to you, not to the camera. The head box is built from your own head width, so it works whether you filmed from six feet or sixteen. If a landmark isn't clearly visible at address, the lines are withheld rather than guessed at, and your report simply won't show them.
The order we fix things in
Measurement is only half the method. The other half is the teaching doctrine our founder built across roughly 8,000 real lessons, and it decides what your report leads with:
- 01
Weight shift first. If the low point and weight shift are wrong, nothing else matters yet. A sway outranks a louder-looking fault every time.
- 02
The chain, P1 → P9. The swing is nine linked positions; we always fix the earliest broken link first, because a break at P2 can be the real cause of what you see at P6.
- 03
Two thoughts max. You leave every report with one priority and one feel. The way a real lesson ends.
See it on your own swing
Three free analyses every month, no card required. Every number in your report is measured exactly the way this page describes.