By Andrew · Founder of Fore-ward Thinking, a golfer who lives in launch monitor data and built an AI coach that remembers every session.
This glossary defines every number your launch monitor reports (what it measures and the unit) so you can read any shot with confidence. Metrics split into ball data (what the ball did) and club delivery data (how the club arrived); not every monitor measures the delivery numbers. For what's good by club, see the per club table in the GSPro data analysis guide.
Figure 1 · five metrics · family, unit, who measures it
Ball data is what the ball did; club delivery data is how the club arrived, and not every monitor measures it. The amber cells are the club numbers a camera unit measures and radar estimates or omits. Smash factor is club dependent: a driver tops near 1.50, a 7 iron sits about 1.33 at a classic loft, a wedge about 1.24.
Ball data
Ball speed: How fast the ball leaves the clubface, in mph. The biggest single predictor of distance and the raw result of a good strike. A driver swung 100 mph at 1.50 smash produces 150 mph ball speed.
Club speed: How fast the head is moving just before impact, in mph. More speed raises distance potential, but only a centered strike converts it, which is what smash factor measures.
Launch angle: The vertical angle, in degrees, the ball leaves the face relative to the ground. It rises with the loft delivered at impact. Too low won't carry; too high balloons.
Launch direction: The horizontal angle the ball starts on, left or right of target. Under modern ball flight understanding, the ball starts primarily where the face points at impact, so start line is mostly a face angle story.
Backspin: The rate the ball spins backward, in rpm; creates height and stopping power and rises with loft. Driver ~2,000 to 3,000; 7 iron ~6,000 to 7,500 at a classic 33 to 35 degree loft; wedge ~9,000 to 11,500. A strong lofted 7 iron (28 to 31 degrees) carries what a 5 or 6 iron used to, so its healthy band is lower: 5,200 to 6,800. Check the loft on the sole before you read low iron spin as a thin or delofted strike. (Source: Trackman.)
Side spin / spin axis: The sideways component of spin that curves the ball, usually shown as axis tilt. Right tilt fades or slices for a right hander; left draws or hooks. It's set by face angle relative to club path. Full breakdown with thresholds: launch monitor spin axis, explained.
Spin rate: Total ball rotation, in rpm, combining backspin and side component. Most monitors report backspin and spin axis separately, which is more useful for diagnosing flight than a single total.
Carry vs total: Carry is air distance; total adds roll. On a simulator, carry is the honest number: total depends on the firmness GSPro models. Plan your gapping off carry.
Apex / peak height: The highest point of the shot, in feet or yards. Reflects launch and spin together; a healthy iron flight needs enough height to land softly.
Descent angle: How steeply the ball falls, in degrees. Steeper lands softer and stops faster: wedges land near 50°, a driver much shallower. Too flat an iron descent won't hold a green.
Club delivery data
Driver smashnear 1.50where a well struck driver tops out
7 iron smash~1.33at a classic 33 to 35 degree loft (a 1.30 to 1.38 band)
Smash factor: Ball speed divided by club speed; how efficiently energy transfers at impact. Club dependent: driver tops near 1.50, 7 iron ~1.33 at a classic 33 to 35 degree loft (a 1.30 to 1.38 band), wedge ~1.24 (Trackman Tour averages). A strong lofted 7 iron (28 to 31 degrees) carries what a 5 or 6 iron used to, so its healthy band is 1.36 to 1.41. Read a high iron smash of 1.40 plus as a thin or delofted strike only at traditional loft: at 28 to 29 degrees the fair ceiling is the 5 to 6 iron row's 1.41. The full per club table is in the GSPro guide.
Club path: The horizontal direction the clubhead is moving at impact, in degrees relative to the target line. Positive is in to out (right of target, for a right hander); negative is out to in. It's one half of what shapes the shot: where the club is going, not where the face points. (Source: Trackman.)
Face angle: Where the clubface points at impact relative to the target line, in degrees. The dominant factor in start line (the ball starts roughly where the face points) and one input to curve. (Source: Trackman.)
Face to path: The difference between face angle and club path at impact. The primary driver of curve: the ball curves away from the path, toward the face. Face open to the path fades or slices; closed draws or hooks; square flies straight. (Source: Trackman.)
Angle of attack: The up or down direction the clubhead moves at impact, in degrees. Irons are struck descending (negative) to compress the ball and take a divot in front; the driver is best struck level to slightly upward (positive) to add carry and lower spin. Not every monitor measures it. (Source: Trackman.)
Dynamic loft: The actual loft on the face at impact, which can differ from the club's stated loft. More dynamic loft raises launch and usually spin, which is why casting, flipping or scooping add launch and spin, never reduce them. (Source: Trackman.)
Dispersion: How scattered your shots are around their average, side to side and in distance. The truest measure of consistency: a tight group of slightly off shots scores better than a wide spread of occasional perfect ones.
Quick reference
Which metrics ball first units measure vs which need a camera unit. See the GSPro guide for device classes.
Metric
Family
Unit
Typically measured by
Ball speed
Ball
mph
All monitors
Launch angle
Ball
degrees
All monitors
Backspin / spin axis
Ball
rpm / degrees
All monitors
Carry
Ball
yards
All monitors
Descent angle
Ball
degrees
Most monitors
Smash factor
Club
ratio
All (needs club speed)
Club path
Club
degrees
Camera; radar estimates/omits
Face angle
Club
degrees
Camera; radar estimates/omits
Face to path
Club
degrees
Camera; radar estimates/omits
Angle of attack
Club
degrees
Camera; radar estimates/omits
Frequently asked questions
What's the difference between club path and face angle?
Club path is the direction the clubhead travels at impact; face angle is where the face points. The face dominates the start line; the gap between face and path (face to path) curves the ball.
Why is low spin bad on an iron?
Iron backspin creates the steep descent that stops the ball on the green. Too little spin gives a flat landing and less control, but check the loft before you call it a fault: a strong lofted 7 iron at 28 to 31 degrees spins 5,200 to 6,800 by design, where a classic 33 to 35 degree 7 iron spins 6,000 to 7,500. Below its own band, a thin or delofted strike is the usual cause. (The driver is the opposite: lower spin there usually adds distance.)
Which launch monitor metrics are measured vs estimated?
Ball data (ball speed, launch, spin, carry) is measured by virtually every monitor. Club delivery data (club path, face angle, angle of attack) is measured directly only by camera/photometric units; radar and budget units often estimate or omit it.
If you'd rather not memorize any of this: I built Fore-ward Thinking, an AI coach called Chip that reads these numbers across your sessions and tells you what they mean for your game, coaching from your data, not from swing video. Disclosure: I'm the founder.