MLB.com

1.01
Baseball is a game between two teams of nine players each, under direction of a manager, played on an enclosed field in accordance with these rules, under jurisdiction of one or more umpires.

1.02
The objective of each team is to win by scoring more runs than the opponent.

1.03
The winner of the game shall be that team which shall have scored, in accordance with these rules, the greater number of runs at the conclusion of a regulation game.

1.04
THE PLAYING FIELD. The field shall be laid out according to the instructions below, supplemented by Diagrams No. 1, No. 2 and No. 3 on adjoining pages. The infield shall be a 90-foot square. The outfield shall be the area between two foul lines formed by extending two sides of the square, as in Diagram 1. The distance from home base to the nearest fence, stand or other obstruction on fair territory shall be 250 feet or more. A distance of 320 feet or more along the foul lines, and 400 feet or more to center field is preferable. The infield shall be graded so that the base lines and home plate are level. The pitcher's plate shall be 10 inches above the level of home plate. The degree of slope from a point 6 inches in front of the pitcher's plate to a point 6 feet toward home plate shall be 1 inch to 1 foot, and such degree of slope shall be uniform. The infield and outfield, including the boundary lines, are fair territory and all other area is foul territory. It is desirable that the line from home base through the pitchers plate to second base shall run East-Northeast. It is recommended that the distance from home base to the backstop, and from the base lines to the nearest fence, stand or other obstruction on foul territory shall be 60 feet or more. See Diagram 1. When location of home base is determined, with a steel tape measure 127 feet, 338 inches in desired direction to establish second base. From home base, measure 90 feet toward first base; from second base, measure 90 feet toward first base; the intersection of these lines establishes first base. From home base, measure 90 feet toward third base; from second base, measure 90 feet toward third base; the intersection of these lines establishes third base. The distance between first base and third base is 127 feet, 338 inches. All measurements from home base shall be taken from the point where the first and third base lines intersect. The catcher's box, the batters' boxes, the coaches' boxes, the three-foot first base lines and the next batter's boxes shall be laid out as shown in Diagrams 1 and 2. The foul lines and all other playing lines indicated in the diagrams by solid black lines shall be marked with wet, unslaked lime, chalk or other white material. The grass lines and dimensions shown on the diagrams are those used in many fields, but they are not mandatory and each club shall determine the size and shape of the grassed and bare areas of its playing field. NOTE (a) Any Playing Field constructed by a professional club after June 1, 1958, shall provide a minimum distance of 325 feet from home base to the nearest fence, stand or other obstruction on the right and left field foul lines, and a minimum distance of 400 feet to the center field fence. (b) No existing playing field shall be remodeled after June 1, 1958, in such manner as to reduce the distance from home base to the foul poles and to the center field fence below the minimum specified in paragraph (a) above.

1.06
First, second and third bases shall be marked by white canvas bags, securely attached to the ground as indicated in Diagram 2. The first and third base bags shall be entirely within the infield. The second base bag shall be centered on second base. The bags shall be 15 inches square, not less than three nor more than five inches thick, and filled with soft material.

1.07
The pitcher’s plate shall be a rectangular slab of whitened rubber, 24 inches by 6 inches. It shall be set in the ground as shown in Diagrams 1 and 2, so that the distance between the pitcher’s plate and home base (the rear point of home plate) shall be 60 feet, 6 inches.

1.08
The home club shall furnish players’ benches, one each for the home and visiting teams. Such benches shall not be less than 25 feet from the base lines. They shall be roofed and shall be enclosed at the back and ends.

1.09
The ball shall be a sphere formed by yarn wound around a small core of cork, rubber or similar material, covered with two stripes of white horsehide or cowhide, tightly stitched together. It shall weigh not less than five nor more than 5 1/4 ounces avoirdupois and measure not less than nine nor more than 9 1/4 inches in circumference.

1.10
(a) The bat shall be a smooth, round stick not more than 23/4 inches in diameter at the thickest part and not more than 42 inches in length. The bat shall be one piece of solid wood.
NOTE: No laminated or experimental bats shall be used in a professional game (either championship season or exhibition games) until the manufacturer has secured approval from the Rules Committee of his design and methods of manufacture.
(b) Cupped Bats. An indentation in the end of the bat up to one inch in depth is permitted and may be no wider than two inches and no less than one inch in diameter. The indentation must be curved with no foreign substance added.
(c) The bat handle, for not more than 18 inches from its end, may be covered or treated with any material or substance to improve the grip. Any such material or substance, which extends past the 18 inch limitation, shall cause the bat to be removed from the game.
NOTE: If the umpire discovers that the bat does not conform to (c) above until a time during or after which the bat has been used in play, it shall not be grounds for declaring the batter out, or ejected from the game.
(d) No colored bat may be used in a professional game unless approved by the Rules Committee.

1.11
(a) (1) All players on a team shall wear uniforms identical in color, trim and style, and all players uniforms shall include minimal sixinch numbers on their backs. (2) Any part of an undershirt exposed to view shall be of a uniform solid color for all players on a team. Any player other than the pitcher may have numbers, letters, insignia attached to the sleeve of the undershirt. (3) No player whose uniform does not conform to that of his teammates shall be permitted to participate in a game.
(b) A league may provide that (1) each team shall wear a distinctive uniform at all times, or (2) that each team shall have two sets of uniforms, white for home games and a different color for road games.
(c) (1) Sleeve lengths may vary for individual players, but the sleeves of each individual player shall be approximately the same length. (2) No player shall wear ragged, frayed or slit sleeves.
(d) No player shall attach to his uniform tape or other material of a different color from his uniform.
(e) No part of the uniform shall include a pattern that imitates or suggests the shape of a baseball.
(f) Glass buttons and polished metal shall not be used on a uniform.
(g) No player shall attach anything to the heel or toe of his shoe other than the ordinary shoe plate or toe plate. Shoes with pointed spikes similar to golf or track shoes shall not be worn.
(h) No part of the uniform shall include patches or designs relating to commercial advertisements.
(i) A league may provide that the uniforms of its member teams include the names of its players on their backs. Any name other than the last name of the player must be approved by the League President. If adopted, all uniforms for a team must have the names of its players.

1.12
The catcher may wear a leather mitt not more than 38 inches in circumference, nor more than 151/2 inches from top to bottom. Such limits shall include all lacing and any leather band or facing attached to the outer edge of the mitt. The space between the thumb section and the finger section of the mitt shall not exceed six inches at the top of the mitt and four inches at the base of the thumb crotch. The web shall measure not more than seven inches across the top or more than six inches from its top to the base of the thumb crotch. The web may be either a lacing or lacing through leather tunnels, or a center piece of leather which may be an extension of the palm, connected to the mitt with lacing and constructed so that it will not exceed any of the above mentioned measurements.

1.13
The first baseman may wear a leather glove or mitt not more than twelve inches long from top to bottom and not more than eight inches wide across the palm, measured from the base of the thumb crotch to the outer edge of the mitt. The space between the thumb section and the finger section of the mitt shall not exceed four inches at the top of the mitt and 31/2 inches at the base of the thumb crotch. The mitt shall be constructed so that this space is permanently fixed and cannot be enlarged, extended, widened, or deepened by the use of any materials or process whatever. The web of the mitt shall measure not more than five inches from its top to the base of the thumb crotch. The web may be either a lacing, lacing through leather tunnels, or a center piece of leather which may be an extension of the palm connected to the mitt with lacing and constructed so that it will not exceed the above mentioned measurements. The webbing shall not be constructed of wound or wrapped lacing

1.14
Each fielder, other than the first baseman or catcher, may use or wear a leather glove. The measurements covering size of glove shall be made by measuring front side or ball receiving side of glove. The tool or measuring tape shall be placed to contact the surface or feature of item being measured and follow all contours in the process. The glove shall not measure more than 12 inches from the tip of any one of the four fingers, through the ball pocket to the bottom edge or heel of glove. The glove shall not measure more than 73/4 inches wide, measured from the inside seam at base of first finger, along base of other fingers, to the outside edge of little finger edge of glove. The space or area between the thumb and first finger, called crotch, may be filled with leather webbing or back stop. The webbing may be constructed of two plies of standard leather to close the crotch area entirely, or it may be constructed of a series of tunnels made of leather, or a series of panels of leather, or of lacing leather thongs. The webbing may not be constructed of wound or wrapped lacing to make a net type of trap. When webbing is made to cover entire crotch area, the webbing can be constructed so as to be flexible. When constructed of a series of sections, they must be joined together. These sections may not be so constructed to allow depression to be developed by curvatures in the section sides. The webbing shall be made to control the size of the crotch opening. The crotch opening shall measure not more than 41/2 inches at the top, not more than 53/4 inches deep, and shall be 31/2 inches wide at its bottom. The opening of crotch shall not be more than 41/2 inches at any point below its top. The webbing shall be secured at each side, and at top and bottom of crotch. The attachment is to be made with leather lacing, these connections to be secured. If they stretch or become loose, they shall be adjusted to their proper condition. The glove can be of any weight.

1.15
(a) The pitcher’s glove may not, exclusive of piping, be white, gray, nor, in the judgment of an umpire, distracting in any manner.
(b) No pitcher shall attach to his glove any foreign material of a color different from the glove.
(c) The umpire-in-chief shall cause a glove that violates Rules 1.15(a) or 1.15(b) to be removed from the game, either on his own initiative, at the recommendation of another umpire or upon complaint of the opposing manager that the umpire-in-chief agrees has merit.

1.16
A Professional League shall adopt the following rule pertaining to the use of helmets:
(a) All players shall use some type of protective helmet while at bat.
(b) All players in National Association Leagues shall wear a double ear-flap helmet while at bat.
(c) All players entering the Major Leagues commencing with the 1983 championship season and every succeeding season thereafter must wear a single ear-flap helmet (or at the player’s option, a double ear-flap helmet), except those players who were in the Major League during the 1982 season, and who, as recorded in that season, objected to wearing a single ear-flap helmet.
(d) All catchers shall wear a catcher’s protective helmet, while fielding their position.
(e) All bat/ball boys or girls shall wear a protective helmet while performing their duties.
Rule 1.16 Comment: If the umpire observes any violation of these rules, he shall direct the violation to be corrected. If the violation is not corrected within a reasonable time, in the umpire’s judgment, the umpire shall eject the offender from the game, and disciplinary action, as appropriate, will be recommended.

1.17
Playing equipment including but not limited to the bases, pitcher’s plate, baseball, bats, uniforms, catcher’s mitts, first baseman’s gloves, infielders and outfielders gloves and protective helmets, as detailed in the provisions of this rule, shall not contain any undue commercialization of the product. Designations by the manufacturer on any such equipment must be in good taste as to the size and content of the manufacturer’s logo or the brand name of the item. The provisions of this Section 1.17 shall apply to professional leagues only.
NOTE: Manufacturers who plan innovative changes in baseball equipment for professional baseball leagues should submit same to the Official Playing Rules Committee prior to production.