Junior Baseball rules versus Adult Baseball
Length of Game-
A regulation Little League game is six innings. A major league game is nine innings. A 'mercy rule' applies if one team is ahead by 10 or more runs by the end of the fourth inning.
Mandatory Play Rule-
In Little League every player on the team roster must have at least one plate appearance and play three consecutive outs on defense in each game.
A Little League field is roughly one-third smaller than a Major League field. The basepaths are 60 feet long rather than the usual 90 feet in adult baseball. The pitching distance is 46 feet compared to the 60 feet, 6 inches distance in adult baseball. The home run fence is normally 200 feet compared to the 300 feet+ distance of adult baseball fields. Edinburgh Little League also uses a safety base at 1st base to aid in player safety which is twice the width of a regular base.
Little League bats are smaller and thinner than adult bats but the ball is the same size and weight. Gloves vary in size and style depending upon the position played and age of the player.
When the pitcher is ready to pitch, a baserunner may not leave his/her base until the pitch reaches the batter. If a fielder is waiting at the base with the ball, an advancing runner must attempt to avoid contact. A runner may not slide head-first except when retreating to a previously held base. In adult baseball, runners can stand off their base at their own risk to reduce the distance to the next base.
The strike zone is between the batter's armpits and knees. In Little League, leagues can opt to adopt a rule whereby the batter is out after the third strike regardless of whether the pitched ball is held by the catcher.
Players who have been substituted may return to the game under certain conditions, though a pitcher who has left the game may not return to pitch nor move to the catcher position (see below).
Local leagues have a certain amount of flexibility in applying their own rule variants. For example Edinburgh Junior Baseball operates a 6 run rule in each inning whereby once one team scores 6 runs, their turn at bat is over. This rule does not apply in the 6th inning.
Pitchers are limited to a specific pitch count per game and a mandatory rest period between outings. These vary with age and the rest period also depends on the number of pitches thrown. Pitchers are also not permitted to move from pitcher to catcher after having thrown 41 or more pitches in a game so as to avoid fatigue and injury. Pitch count details are below...
Little League - Pitch Count and Rest Day Requirements
League Age Pitch Count
Number of Pitches in a Day Rest Day Requirements
66 or more 4
51 to 65 3
36 to 50 2
21 to 35 1
1 to 20 None