What it measures
Height, often called apex, is the vertical distance between the launch level and the very top of the ball's flight. It is measured in feet, yards or meters.
It is measured relative to where the ball started, not relative to the ground where it lands. A shot hit to an elevated green and a shot hit to a sunken one can have the same apex. There is no left or right sign here, so it reads the same for right-handed and left-handed golfers.
Typical numbers
Long-standing PGA Tour averages put apex at about 32 yards for driver, about 32 yards for a 7 iron and about 29 yards for a pitching wedge. More recent tour averages put driver apex a few yards higher, around 35 yards. The surprising part is that good players hit almost every club to a similar peak height. Longer clubs get there with speed, shorter clubs with launch and spin.
LPGA Tour players generally peak several yards lower because they swing slower. Everyday golfers vary widely. Many see driver apex somewhere around 18 to 28 yards and mid-iron apex in a similar or slightly lower band. Slower swing speeds usually mean a lower peak, not a higher one.
What changes it
Three launch numbers drive height. More ball speed sends the ball higher and farther. A higher launch angle starts it on a steeper climb. More backspin creates more lift, which raises and extends the climb. Air conditions matter too: thin, warm air lets the ball fly lower and farther for the same launch, while a headwind adds lift and pushes the peak up.
In the swing, dynamic loft (how much loft the club actually delivers at impact) and attack angle set launch, while spin loft sets spin. Adding shaft lean or hitting down more steeply tends to lower launch and lower height. Flipping the hands at impact tends to add loft, spin and height with irons, and often costs distance.
What it changes
Height is linked closely to landing angle. A taller flight usually comes down more steeply, so the ball rolls less after landing. A flatter flight lands shallower and runs out more.
With driver, too little height means the ball falls out of the air before it can use its speed, which shortens carry. Too much height, usually from excess spin, also costs distance and makes the ball balloon in wind. With irons and wedges, enough height is what lets the ball stop near where it lands.
How to use it
Treat height as a window, not a number to maximize. Note your average apex for driver, a mid iron and a wedge. If your irons peak much lower than your driver, the ball is probably coming in too flat to hold greens. If your driver peaks much higher than your irons, spin may be too high.
Bay drill: hit five shots with one 7 iron at your normal flight, then five trying to flight it lower and five higher, without changing clubs. Watch height and carry together. Learning to move apex a few yards on purpose is the skill you need for wind and for hitting under or over trees on the course.