Section 1: Introduction
Baseball is a bat-and-ball team sport played between two teams of nine players who take turns batting and fielding. The sport is governed internationally by the World Baseball Softball Confederation (WBSC), the IOC-recognized international federation for baseball and softball. This rulebook is based on the Official Rules of Baseball 2025-2026, the edition mandatory for application at all WBSC-sanctioned baseball tournaments across the 2025 and 2026 seasons (WBSC Official Rules of Baseball 2025-2026, Preface).
The objective of the game is for a team to score more runs than its opponent by having its batters safely reach and advance around four bases arranged in a diamond — first base, second base, third base, and home base — while the opposing team's pitcher and fielders attempt to record three outs per half-inning (Rule 1.01, Objectives of the Game). A standard game consists of nine innings, each divided into a top half (visiting team bats) and a bottom half (home team bats) (Rule 4.10).
WBSC baseball follows the same core rule structure used by many National Federations worldwide, organized into numbered Rules (1 through 10) covering objectives, definitions, game preliminaries, starting and ending a game, playing the game, improper and illegal action, ending the game, the pitcher, the umpire, and the official scorer, with WBSC-specific Special Playing Regulations appended for international competition (e.g., mercy rule, extra-inning tiebreaker, and game-time limits).
Section 2: Equipment
Ball (Rule 1.09): The baseball must be a sphere formed by yarn wound around a small core of cork, rubber, or similar material, covered with two strips of white horsehide or cowhide, tightly stitched together. It must weigh between 5 and 5.25 ounces (141.7–148.8 g) and measure between 9 and 9.25 inches (22.9–23.5 cm) in circumference.
Bat (Rule 1.10): The bat must be a smooth, round stick not more than 2.61 inches (6.6 cm) in diameter at its thickest part and not more than 42 inches (106.7 cm) in length. It must be composed of one piece of solid wood, or fashioned from a wood/composite laminate, and must not be adulterated with any substance to improve distance or performance. WBSC competitions specify additional bat-performance standards for non-wood bats used in certain divisions.
Glove: Fielders wear a leather glove or mitt to catch and control the ball; the catcher and first baseman use specially shaped mitts. Glove dimensions are regulated by rule to prevent oversized webbing that could give an unfair advantage.
Batting helmet (Rule 1.16): All batters, on-deck batters, and base runners must wear a protective helmet meeting the approved safety standard while batting or running the bases. Failure to wear a required helmet is subject to warning and, upon repetition, ejection.
Catcher's protective equipment (Rule 1.17): The catcher must wear a protective helmet and mask, a chest protector, and shin guards, along with a catcher's mitt, whenever receiving pitches, whether in the bullpen or during the game.
Uniform and footwear (Rule 1.11): All players on a team must wear uniforms identical in color, trim, and style, with player numbers visibly displayed. Shoes with molded or metal spikes conforming to safety specifications may be worn; pitchers' uniforms are subject to additional restrictions to prevent any material that could distract the batter.
Section 3: Playing Area
The infield (Rule 1.04–1.06): The playing field is a diamond with four bases spaced 90 feet (27.43 m) apart: home base, first base, second base, and third base, connected by foul lines extending from home plate through first and third base. Home plate is a five-sided slab of whitened rubber, 17 inches (43.2 cm) wide across the side facing the pitcher. First, second, and third base are 15-inch (38.1 cm) square canvas or rubber-covered bags.
The pitcher's mound (Rule 1.07–1.08): The pitcher's plate (rubber) is a rectangular slab 24 inches by 6 inches (61 cm by 15.2 cm), set atop a circular mound. The front edge of the pitcher's plate is 60 feet 6 inches (18.44 m) from the rear point of home plate, and the mound is elevated with a regulated slope.
Outfield and foul territory: Foul lines extend from home plate through first and third base to the outfield fence or boundary. The official rules recommend generous foul territory and specify minimum distances from home plate to the backstop and from the baselines to nearest obstructions to protect players making plays near the stands.
Batter's boxes and coaching boxes: Two batter's boxes, one on each side of home plate, and coach's boxes near first and third base are marked with chalk lines per the dimensions specified in Rule 1.04.
Section 4: Players & Officials
Team composition (Rule 4.03): Each team fields nine players at the start of the game, occupying the defensive positions of pitcher, catcher, first baseman, second baseman, third baseman, shortstop, left fielder, center fielder, and right fielder. WBSC competitions permit use of a Designated Hitter (DH) to bat in place of the pitcher, in accordance with the tournament's specific playing rules.
Substitutions (Rule 3.03–3.05): A player who has been removed from the game may not re-enter. Substitutions must be reported to the umpire-in-chief before taking effect, and the batting order must be maintained throughout the game unless a legal substitution occurs.
Umpires (Rule 9.01–9.05): The umpire-in-chief and base umpires have authority over the conduct of the game, including judgment on balls and strikes, safe and out calls, forfeitures, and enforcement of rules. Umpires' judgment decisions on the field of play are final and not subject to protest; only misapplication of a playing rule may be protested through the tournament's designated protest procedure.
Team officials: Each team is directed by a manager, who communicates lineup changes and pitching changes to the umpire, and by coaches stationed in the first- and third-base coaching boxes during offensive play.
Section 5: Rules of Play
Putting the ball in play: Each half-inning begins with the pitcher delivering the ball to the batter from a legal pitching position — the windup position or the set position (Rule 5.07). A pitch delivered while not in a legal pitching position, or an illegal motion by the pitcher with runners on base, is a balk (Rule 6.02), which advances all base runners one base.
Balls and strikes (Rule 5.05, 5.09): A pitch outside the strike zone that the batter does not swing at is called a ball; four balls award the batter first base (base on balls). A pitch in the strike zone, or any pitch at which the batter swings and misses, or any foul ball with fewer than two strikes, is a strike; three strikes constitute a strikeout, which is an out.
Fair and foul balls: A batted ball that settles on or is touched while over fair territory (between the foul lines) is a fair ball and remains live for play; a ball that settles in foul territory, or is touched there, is a foul ball, generally counted as a strike (unless it would be the third strike, in which case the batter is not out except on a foul tip or bunt attempt).
Advancing and putting out runners: A batter becomes a runner upon a fair-batted ball, a base on balls, being hit by a pitch, or catcher's interference. Runners may advance at their own risk on batted balls, wild pitches, passed balls, or when forced by a following batter-runner. A runner is out if tagged with the ball while off base, forced out at a base ahead of a batted ground ball, or caught off base on an appeal or pickoff.
WBSC Special Playing Regulations: International WBSC tournament competitions apply supplementary regulations not found in domestic amateur or professional codes, including a mercy rule that ends the game early when one team leads by a specified margin (commonly ten runs) after seven innings, and a tiebreaker procedure in extra innings that places a runner on second base to start each half-inning until the tie is broken (WBSC Official Rules of Baseball 2025-2026, Special Playing Rules).
Section 6: Scoring
Runs (Rule 5.06 & Rule 9.02, Official Scorer): A run is scored each time a runner legally touches first, second, third, and home base, in that order, before the third out is made in the half-inning, except when the third out is a force out or the result of the batter-runner being put out before reaching first base, in which case a run scoring on the same play does not count.
Winning the game (Rule 4.10): The team that scores the greater number of runs in a regulation game (typically nine innings, or seven innings at some age divisions per tournament regulations) is the winner. If the score is tied after the regulation number of innings, extra innings are played until a winner is determined, subject to any applicable tiebreaker procedure or time limit.
Called and suspended games: A game may be called by the umpire-in-chief for weather, darkness, or other conditions that make continued play unsafe. If five or more innings have been completed (four and a half if the home team is leading), the game is a regulation game with the score at the time of stoppage; otherwise the game may be resumed or declared a "no game," depending on tournament regulations.
Section 7: Violations & Penalties
Balk (Rule 6.02): An illegal act by the pitcher with one or more runners on base results in a balk; the ball is dead, and all runners advance one base.
Interference and obstruction (Rule 6.01): Offensive interference — such as a batter, runner, or teammate hindering a fielder's attempt to make a play — results in the runner or batter being called out and the ball becoming dead. Defensive obstruction, where a fielder impedes a runner's legal progress without possessing the ball to make a play, entitles the obstructed runner (and, in certain cases, other runners) to advance at least one base.
Illegal pitch or illegal substitution: A pitch delivered illegally with no runners on base is called a ball; use of a foreign substance on the ball, or an illegally re-entering player, subjects the offending player and, where specified, the manager to ejection.
Ejections and conduct violations (Rule 6.04–6.06): Unsportsmanlike conduct, arguing balls-and-strikes judgment calls, physical contact with an umpire, or use of an altered/tampered bat results in ejection of the offending player or team member and may include additional disciplinary action under WBSC tournament regulations.
Appeal plays: A defensive team may appeal a runner's failure to touch a base or leaving a base too early on a caught fly ball by properly executing the appeal before the next pitch, play, or the pitcher and all infielders leave fair territory; a successful appeal results in the runner being called out.
Section 8: Safety Considerations
Mandatory protective equipment: Batters, on-deck batters, and base runners must wear an approved batting helmet at all times while batting or running the bases (Rule 1.16); catchers must wear a helmet, mask, chest protector, and shin guards whenever receiving pitches, including warm-up throws (Rule 1.17). Umpires enforce these requirements and may warn or eject players who fail to comply.
Hit-by-pitch and collision rules: A batter hit by a pitch while making a reasonable attempt to avoid the ball is awarded first base (Rule 5.05); rules also govern home-plate and base-path collisions, restricting runners and catchers from initiating avoidable, forcible contact away from a legitimate attempt to reach or defend the base.
Pitcher and player workload: WBSC youth and age-division competitions apply pitch-count and mandatory-rest regulations to reduce overuse injury risk among developing pitchers, as specified in the applicable tournament's Special Playing Regulations.
Weather and field conditions: The umpire-in-chief has authority to suspend or postpone play for unsafe field conditions, inclement weather, or darkness, and to order removal of players or spectators who create a safety hazard.
