As taught at USA Softball and Florida Half Century umpire clinics, one of the most helpful tools for judging pitch height is the six-foot-tall pitching screen.
A pitch’s height is determined at its highest point, which it normally reaches during the first half of its flight toward home plate. The plate umpire is in the best position to focus on that arc because, unlike the batter and catcher, the umpire is not trying to hit or catch the ball.
If the pitch rises above the top bar of the six-foot screen but does not reach twice the screen’s height, it is not an illegal pitch based on height.
Ultimately, that judgment belongs to the plate umpire—and only the plate umpire.
Respect the call, respect the game.