5-iron tee height.
¼ inch ball-bottom on a Par 3. The 2-iron tee in our pack covers this.
The short answer
¼ inch (6.4 mm) ball-bottom. That is the lowest tee in the pack, the one we size for the 2-iron.
Why a mid-iron wants almost nothing
An iron is designed to strike the ball first and the ground second. The low point of the swing arc sits ahead of the ball, which is what produces compression, and on grass it is what produces a divot in front of where the ball was sitting. Anything that lifts the ball away from the surface moves it away from that intended low point.
A quarter inch is deliberately small. It is not there to launch the ball higher. It is there to guarantee that the club never arrives at the mat before it arrives at the ball, while keeping the strike close enough to a real turf lie that the numbers still mean something.
What a too-high tee does to a 5-iron
Raise a mid-iron much past a quarter inch and two things happen together. You add dynamic loft, so launch rises and spin falls, and you start unconsciously adjusting your swing to sweep the ball off the tee rather than compress it. The second one is the expensive problem: you are rehearsing a motion you cannot use from the fairway. The distance you record in the session is not a distance you can repeat on the course.
Why a 5-iron in particular
The 5-iron sits at the boundary where most amateurs stop striking down reliably. It is long enough to tempt a sweeping, help-it-into-the-air action and short enough that a proper descending strike still works. A low, fixed tee removes the temptation. The ball is barely off the deck, so the only way to hit it well is the way you would hit it off grass.
What the mat is hiding from you
A hitting mat has a rubber layer beneath the synthetic pile that does not break the way turf does. Strike a mat an inch behind the ball and the sole skids forward into the ball instead of digging in. The shot leaves reasonably, the launch monitor records something plausible, and you never learn that you were fat. That is the single biggest reason mat practice fails to transfer. Teeing low and consistently does not fix your strike, but it stops the tee from being one more variable you cannot account for.
Read next
The same quarter inch applies through the 6-iron and 7-iron. By the 9-iron and the wedges you want the ball flush with the mat.
How high should you tee a 5-iron on a par 3?
About a quarter inch of ball-bottom, roughly 6.4 mm. Enough that the club cannot reach the ground before the ball, and not enough to change the strike.
Is it wrong to tee an iron up at all?
On grass most players tee mid-irons very low or not at all. On a hitting mat a small tee is the safer choice, because a mat converts a fat strike into a bounce rather than a divot.
Does teeing a 5-iron higher add distance?
It usually costs distance. A higher tee adds dynamic loft and reduces spin, which tends to produce a weaker, higher ball flight rather than a longer one.