Arc Height Regulation
Also known as: arc window, pitch arc height
Arc height regulation defines the required minimum and maximum height a slow-pitch delivery must reach — usually 6 to 12 feet — to be called a legal pitch.
The arc window exists to make the pitch predictable and hittable: too flat and it plays like fast-pitch. Too high and it falls almost straight down. This gives batters no horizontal timing reference. Pitchers aim for the middle of the window (8–10 feet) because it is forgiving, repeatable, and keeps batters guessing about the descent angle. Arc measurement is a judgment call by the umpire, so consistency beats extreme heights.
Pick a visual target — like the top of the chain-link fence or the top of the backstop — and aim your pitch to peak at or just below that reference on every delivery.
Develop three distinct arc heights (low legal, mid, high) and learn to vary them intentionally within a single at-bat to disrupt the batter's timing rhythm without changing your arm speed.
Example — During pre-game warm-ups
A pitcher reliably places the ball at 9 feet of arc, the sweet spot of the 6-to-12-foot legal window. This keeps the umpire happy and batters uncomfortable.
Why it matters
Pitchers who master the arc window put pressure on hitters rather than gifting free bases. Motion Lab does not track the ball, so measure arc height against a reference on your own video.
How it shows up on video
Arc height is best verified from a straight side-on camera angle. The ball should peak clearly above the pitcher's head (roughly 6 feet) and preferably at 8 to 10 feet for a hittable arc. A ball that appears to track at or below the pitcher's shoulder-height at its peak is likely under the minimum. A ball peaking above the backstop frame (usually 10 to 12 feet) may be approaching the maximum in leagues that enforce one.
Common mistakes
- Pitching to the same arc height regardless of batter and game situation. This makes every pitch read the same way and allowing experienced hitters to time it perfectly
- Sacrificing arc height for speed in a tight game, which risks an illegal-pitch call and gives the offense a free base
- Not adjusting arc height when pitching into headwinds or tailwinds, allowing wind to push the arc outside legal limits without the pitcher realizing it
- Confusing arc height with backspin: adding backspin can increase visual arc height without actually raising the peak. This can mislead pitchers who judge arc by feel rather than measurement
In SwingVantage Motion Lab
Motion Lab does not track the ball, so it cannot measure how high a pitch peaks. Use the side-on reference check on your own video.
Related terms
- ArcThe arc is the high, looping flight path a legal slow-pitch delivery must follow. USA Softball requires a peak between 6 and 12 feet. USSSA instead requires at least 3 feet of arc above the release point and caps height at 10 feet above the ground. Hitters time their swing to the ball's descent, not its rise.
- Legal DeliveryA legal delivery in slow-pitch softball is a pitch that is released underhand with a smooth, continuous motion and arrives within the required arc height — usually between 6 and 12 feet — over the plate.
- Pitch TrackingPitch tracking is following the slow-pitch ball with your eyes from release, through its peak, to contact. It is the key to timing a steeply falling ball.
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