Section 3: Playing Area
3.1 The Playing Field (OBR Rule 2.01)
Per OBR Rule 2.01, the playing field is laid out per the Official Baseball Rules diagram. The infield is a 90-foot (27.432 m) square, with bases at each corner. The bases are numbered counterclockwise: first base (right), second base (center), third base (left), and home plate. The pitcher's plate (rubber) is located at the center of the diamond (OBR Rule 2.01).
3.2 The Bases (OBR Rule 2.03)
Per OBR Rule 2.02:
- Home plate: A 17-inch (43.18 cm) square of whitened rubber, set in the ground so the front edge is even with the rear corner of the batter's box. The sides extending back must be beveled (OBR Rule 2.03).
- First, second, and third base: Must be 15 inches (38.10 cm) square, between 3 and 5 inches (7.62–12.70 cm) thick, and filled with soft material. They must be securely attached to the ground (OBR Rule 2.03).
- Larger bases (effective 2023): First, second, and third base were increased from 15 inches to 18 inches (45.72 cm) square beginning with the 2023 season, as part of MLB's pace-of-play and safety initiatives. Home plate dimensions remain unchanged (OBR Rule 2.03).
- The distance from home plate to second base and from first base to third base is 127 feet, 3⅜ inches (38.795 m) (OBR Rule 2.03).
3.3 The Pitcher's Mound (OBR Rule 2.04)
Per OBR Rule 2.04, the pitcher's plate (rubber) shall be a rectangular slab of whitened rubber, 24 inches (60.96 cm) by 6 inches (15.24 cm). It shall be set in the ground so the front edge is 60 feet, 6 inches (18.44 m) from the rear point of home plate. The top of the pitcher's mound shall be 10 inches (25.4 cm) higher than home plate. The slope of the mound begins 6 inches (15.24 cm) in front of the pitcher's plate and descends at a rate of 1 inch per foot (8.33 cm per 30.48 cm) for a distance of at least 6 feet (182.88 cm) (OBR Rule 2.04).
3.4 The Batter's Box, Catcher's Box, and Coaches' Boxes (OBR Rule 2.05–2.07)
- Batter's box (Rule 2.05): 4 feet (121.92 cm) wide by 6 feet (182.88 cm) long, located on either side of home plate.
- Catcher's box (Rule 2.06): 8 feet (243.84 cm) in length and 43 inches (109.22 cm) wide.
- Coaches' boxes (Rule 2.07): Located adjacent to first and third base, each 8 feet (243.84 cm) by 15 feet (457.20 cm).
- On-deck circles: Two circles, 5 feet (152.40 cm) in diameter, located near the dugouts for the next batter to warm up (OBR Rule 2.05–2.07).
3.5 Fair and Foul Territory (OBR Rule 2.01, Definitions)
Per the OBR Definitions of Terms, "Fair Territory" is that part of the playing field within and including the first base and third base lines from home base to the bottom of the playing field fence, and as further determined by the foul lines. "Foul Territory" is that part of the playing field outside the first base and third base lines extended to the fence and perpendicularly upward. The foul poles at the outfield fence, which are at least 325 feet (99.06 m) from home plate along the foul lines in stadiums built after June 1, 1958, mark the boundary between fair and foul territory in the outfield (OBR Rule 2.01, Definitions).
3.6 The Dugout
Each team has a dugout, one on each side of the playing field. Only players in uniform, managers, coaches, trainers, and batboys may occupy the dugout during a game (OBR Rule 4.05). Dugouts must be enclosed and below field level in professional stadiums.