Legal Delivery
Also known as: legal pitch, legal slow-pitch delivery
A 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. This means typically between 6 and 12 feet. This means over the plate.
Umpires judge a delivery on three factors. This means the release (must be underhand and from below the hip), the motion (one smooth, continuous forward swing. This means no snap or spin). The arc (the ball must travel through the legal height window). Any pitch outside those parameters is called illegal, and the batter may take the pitch as a ball or swing at it. Pitchers who focus on consistent spin-free releases and repeatable arc control give their team more innings without free bases.
Aim to release the ball with your thumb pointing upward at the moment of release. This means this naturally produces the upward trajectory needed for a legal arc.
Learn to vary your arc height between the 6-foot minimum and 12-foot maximum. At the same time, keeping release speed consistent. As a result, batters cannot read the pitch type from the arc alone.
Example
The pitcher lobs the ball smoothly underhand; it rises to 9 feet and drops into the zone — the umpire signals a legal pitch.
Why it matters
Illegal pitches hand free bases and momentum to the opposition. SwingVantage can flag delivery-consistency faults so your pitcher repeats a legal motion every time.
How it shows up on video
A legal slow-pitch delivery on video shows a smooth underhand release with the ball rising to a visible arc before descending toward the plate. The pitch should travel in a clear upward arc reaching 6 to 12 feet before descending. Compare arc height against a reference object such as the backstop or a known structure to verify compliance.
Common mistakes
- Releasing the ball too flat so the arc never reaches the minimum 6-foot height, drawing an illegal-pitch call from the umpire on every flat delivery
- Over-spinning the ball with a snap of the wrist to add movement. This counts as an intentional spin violation in most associations and results in a dead ball
- Stepping off the rubber before releasing the ball, which constitutes an illegal pitch even if the delivery arc and speed are otherwise legal
- Not calling the pitch when a batter is outside the batter's box at release. This allows an argument that the delivery was illegal due to batter position
In SwingVantage Motion Lab
SwingVantage can measure arc height and ball flight trajectory from uploaded pitch video. This helps pitchers verify their delivery meets the association's minimum arc requirement on every pitch.
Frequently asked questions
What is the legal arc in slow-pitch softball?
Most associations require the pitch to reach a minimum of 6 feet and a maximum of 12 feet above the ground at its highest point, though some leagues vary the window slightly.
Does a pitcher have to wind up in slow pitch?
No windup is required, but the delivery must be a single, continuous underhand motion without stopping or reversing.
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.
- Illegal PitchAn illegal pitch is any delivery that violates the rules. This means most commonly a pitch outside the legal arc window, a spin-thrown ball, or a release from an illegal position.
- Arc Height RegulationArc height regulation defines the required minimum and maximum height a slow-pitch delivery must reach. This means typically 6 to 12 feet. This means to be called a legal pitch.
- Pitching RubberThe pitching rubber is the white rubber slab on the pitcher's mound from which the pitcher must begin and complete a legal delivery. Leaving or dragging off the rubber incorrectly results in an illegal pitch.
Related guides & benchmarks
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