Golf by the numbers, Launch monitor metrics and what they mean

Say what?

Have you ever been in the situation where you and a friend are hitting balls on a golf simulator and you see the numbers pop on the stat screen and then your friend just starts interpreting them like he’s the golf version of Bill Nye, but you’re about 95% sure he’s full of it. It might have been when he said AoA is your Axis of Alignment, or when he said your “Face to Target” number is where your eyes are at impact. It’s not like you know if he’s right or not, but when you asked some probing questions to get more understanding, he was a little less confident in his answers. “The lie detector said… That was a lie!” -Maury. Your friend has no idea what he’s talking about but after reading this, you will.

Ball Data

Not all launch monitors are created equal, but if the machine is a true launch monitor, it will capture ball data. Some launch monitors combine metrics, some call the metrics a different name, some metrics may be omitted, and some may have more than what is covered here. The metrics presented here are the most typical though.

Carry Distance

The amount of distance the ball travels through the air. This is a calculation based on the other metrics. This is the first metric that most people see and can understand right off the bat. Big numbers draw cheers from the crowd--small numbers, their jeers.

Total Distance

This is a calculation based on all the ball data that was captured to figure out carry distance then the machine will also try to apply factors for surface variables, such as ground hardness or surface type, to come up with how much the ball rolled after it hits the ground.

Ball Speed

The measurement of the golf ball’s velocity just after impact. Ball speed is the main component in generating distance. Simple. “Ball go fast, ball go far. Ball go slow, ball go not far.” -me

Total Spin

The amount of total spin created around the tilt axis is expressed as total spin. This will determine the curve and lift of the shot. Higher spins affect the flight path and/or stopping distance to a higher degree. It is typically presented in RPM (revolutions per minute), and it is the number of revolutions the ball would undergo in a minute if not acted upon by another force, i.e. the ground. It’s measured instantaneously when the ball is impacted. One thing I see often is an emphasis on this number without context. Total spin is only the magnitude of the spin rate. Context matters when it comes to spin. Used in conjunction with spin axis, you can get a much better idea of what is going on.

Spin (Tilt) Axis

One of the most important pieces of data measure is spin (tilt) axis. The spin (tilt) axis is the axis that the golf ball rotates around to create shot curvature and lift. The data output is a measure of degree relative to straight up, so a positive number means the ball is spinning to the right for a right-handed golfer, resulting in a fade or slice. A negative number means the ball is spinning to left for a right-handed golfer, resulting in a draw or hook. Using the spin (tilt) axis along with the total spin, the launch monitor derives a number to display for back spin and side spin.

Back Spin

A component of total spin that defines ball lift and trajectory. Mathematically, it’s calculated like this: Back Spin = (Total spin) x cos((spin tilt axis) x (pi/180)). The spin tilt axis is multiplied by pi divided by 180 to convert the degrees to radians.

Side Spin

A component of total spin that defines ball curvature or shot shape; related to the spin-tilt axis. Mathematically, it’s calculated like this: Side Spin = (Total spin) x sin((spin tilt axis) x (pi/180)). The spin tilt axis is multiplied by pi divided by 180 to convert the degrees to radians.

Vertical Launch Angle

Commonly referred to as "launch angle" for short, this metric is the initial vertical angle of ascent relative to the ground plane measured in degrees. The launch angle, combined with ball spin and speed, will determine the ball's carry and total distance.

Horizontal Launch Angle

Also know as "Azimuth," side angle, or deviation angle, it's the initial horizontal angle relative to the target line. Horizontal launch angle, combined with side spin, will determine the final ball position range relative to the target line.

Club Data

Club data is a compilation of all the metrics related to your club. Some launch monitors require a sticker placed on the face of your club to pick these metrics up, some can do it without. Regardless of how they are measured, here are the metrics that are commonly found related to the club.

Club (Head) Speed

This is the speed of the club (head) at the moment of impact with the ball. There is a direct correlation to ball speed dependent on how close to the sweet spot the ball was struck.

Smash Factor

This is the correlation between club (head) speed and ball speed. It is simply (ball speed) divided by (club (head) speed). The maximum smash factor set by the USGA is 1.5, although some launch monitors may report values higher than 1.5. This is typically because the data captured is lacking some precision. If you are consistently getting above 1.5 on different launch monitors, your club probably doesn’t conform to USGA standards.

Angle of Attack

Sometimes called attack angle, it is a measure of the angle of the club face when it strikes the ball. A positive angle means the club head was traveling upwards at impact, while a negative angle means the club head was traveling downwards. A positive attack angle will produce a shot that generally has a higher launch angle and lower spin. A negative attack angle will produce a lower launch and higher spin. Depending on what you are trying to accomplish on a given shot, both a positive and negative attack angle can have its benefits.

Face Angle

Face angle is the angle of the club face relative to the target line at the moment of impact. It is measured in degrees, where a positive angle is open, or to the right of target for a right-handed golfer, and a negative angle is closed, or to the left of target for a left-handed golfer.

Club Path

Club path describes the directionality of the club head as it impacts the ball. It can be in-to-out, out-to-in, or straight. It is measured in degrees. In-to-out means that the club head approaches the ball from inside the target line, and after impact is moving outside the target line. Out-to-in is the opposite, where the club head is outside of the target line prior to impact, and moves to inside target line after impact. An in-to-out path is typically associated with a hook or draw, while an out-to-in path is typically associated with a fade or slice.

Dynamic Loft

This is a measure of the loft at impact. Whereas static loft is measured by utilizing a protractor, dynamic loft can change based on how a golfer swings. Dynamic loft can be affected by various metrics we’ve already covered. Perhaps the most obvious is angle of attack, but it can also be affected by club head speed, club path, and some others. Dynamic loft is best used when considered in combination with other metrics such as launch angle and spin rates to understand how the club face is interacting with the ball.

Vertical Swing Plane

The vertical swing plane is the angle between the shaft of the club and the ground at the moment of impact. A steeper swing plane (meaning higher angle) is generally associated with upright swings and shorter clubs like wedges. A shallower swing plane (meaning lower angle) is generally associated with flatter swings and longer clubs like drivers. A consistent swing plane can help maintain ideal loft and face orientation at impact leading to more consistent distances and trajectories. If your vertical swing plane is too steep, you may often see deep divots, high-launching shots, increased spin, and reduced roll on longer shots. If your vertical swing plane is too shallow, you may often see low launch angles and reduced back spin.

Horizontal Swing Plane

This is the direction of the swing arc, relative to the target line. It is very similar to club path but there are some key differences. 1. Horizontal Swing Plane is the direction at the low point of the swing, whereas club path is the direction at impact. 2. Before the low point, club path is to the right of horizontal swing plane. After the low point, club path is to the left of horizontal swing plane. 3. How much the club path is to the right or left of the horizontal swing plane is influenced by the angle of attack and the vertical swing plane.

Clubface to Path

The face to path angle is the difference between face angle and club path at the moment of impact. A positive face to path means the face is pointed to right of the club path, and a negative face to path means the face is pointed to the left of the club path.

Swing Tempo

The ratio of time spent in the backswing versus the downswing. The general consensus for an ideal tempo is a 3:1 ratio, where the backswing is 3 times longer than the downswing.

Impact Location

The location of the clubface where the ball makes contact. Being able to consistently hit the ball in the middle of the club face will lead to the most consistent improvements in distance and accuracy.

Conclusion

If you've made it this far, you've exhausted my knowledge of launch monitor data. Good Luck