What it measures
Low point height compares the height of the clubhead just before impact with the height of the lowest point of the swing arc, as if the club had passed through without hitting the ball or the turf. The result is a small vertical distance, usually measured in inches or centimeters.
It is the vertical partner of low point, which measures the same bottom of the arc along the target line, and of low point side, which measures it left or right. For an iron hit with a downward blow, the bottom of the arc is below the impact position, telling you how far the club would keep traveling down into the turf after the ball.
Typical numbers
The values are small. For a full iron swing with a typical arc and a downward attack angle of around 4 degrees, simple geometry puts the bottom of the arc only a fraction of an inch below the impact position, a few millimeters. Steeper strikes and shorter swing radii make the number larger, shallow strikes make it smaller.
There are no standard tour averages for this parameter, and it varies with club, setup and swing length. It is best judged against your own average for a given club rather than against a single benchmark.
What changes it
Attack angle and low point distance drive it. The steeper the blow and the further past the ball the arc bottoms out, the deeper the low point sits below impact. Swing radius also matters: a wider arc, with long arms and a full extension, bottoms out more gradually than a short, narrow arc.
Changes in posture through the swing, such as standing up, dipping down or losing spine angle, move the whole arc up or down and show up here as inconsistency from shot to shot. With the driver on a tee, the club is normally above its low point at impact.
What it changes
Low point height does not change ball flight by itself. It describes how the club is meeting the ground, which affects strike quality. A consistent value with irons means consistent divot depth on grass and consistent contact height on the face. Large swings in the number point to fat and thin contact, which then show up as lost ball speed, unpredictable spin and inconsistent launch.
Read it alongside impact height on the face and attack angle. A deep low point with a low strike on the face can mean the club is digging; a shallow one with thin contact can mean the arc is too high.
How to use it
Treat low point height as a trend number. Look at the spread across ten shots with the same club more than any single value. Because mats hide heavy contact, it is useful for spotting fat strikes that still produced decent ball flight in the bay but would dig in on real turf.
Bay drill: hit ten 7 irons focusing on keeping your chest height steady from address to impact, then compare the spread of low point height and impact height with a set where you swing freely. A tighter spread means a more repeatable arc and more consistent contact on the course.