Field and bases
Baseball field and bases: the diamond, foul lines and pitching distance
A guide to the main field measurements in baseball: the 90-foot infield square, where the bases and home plate sit, the standard 60 ft 6 in pitching distance, and why some dimensions differ by competition.
The infield is a square
In MLB and WBSC standard adult/top-level rules, the infield is laid out as a 90-foot (27.43 m) square. Home plate, first base, second base and third base form the circuit. Foul lines extend from home plate through first and third base and continue into the outfield.
How the bases are measured
The 90-foot figure describes the official layout between defined reference points, not the clear gap from the front edge of one bag to the next. Base size can depend on the ruleset: MLB currently uses 18-inch square bases at first, second and third, while the 2025–2026 WBSC rules specify 15-inch square bags for its standard U-15-and-above field. Home plate has its own five-sided shape.
Pitcher's plate and mound
For the standard adult field, the pitcher's plate is 60 feet 6 inches (18.44 m) from the back point of home plate. The plate itself is 24 by 6 inches, and MLB and WBSC specifications place its top 10 inches above home-plate level on a regulation mound. Youth formats can use shorter distances and lower mounds.
Why outfields are not identical
Unlike the 90-foot infield layout, outfield fence distances are not identical at every ballpark. MLB and WBSC publish their own minimums or competition-specific dimensions, and youth fields can be smaller. When a dimension matters for a particular game, use the governing competition and venue rules rather than assuming one universal outfield size.