How baseballs are made
A regulation baseball has 108 double stitches, and its cover is stitched by hand.
- stations
- 7
- things upstream
- 72
- raw sources
- 22
- steps from the ground
- 8
The short version
A baseball is a small core of cork and rubber wound tightly in layers of wool yarn, then covered with two figure-eight pieces of white cowhide. Yarn is wound on in several layers. The two leather pieces are sewn together with red thread, using 108 stitches, and the finished ball is weighed and rubbed.
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Form the center
A small round core is molded from cork and rubber. The center decides much of how lively the ball is.
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Wind on the yarn
Machines wrap the core with layers of wool yarn, pulling tight. Early balls were hand-wound, and tighter windings with more rubber went further and faster.
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Cut the cover panels
Cowhide is tanned, dyed white and cut into two pieces shaped like figure-eights. Each is formed from two saddle-shaped halves.
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Glue the cover on
The wound ball is coated with cement so the cover will bond to the yarn.
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Hand-stitch the seams
A worker sews the two panels together with red waxed thread. The raised stitches measure 108 in all, and they affect how the ball flies.
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Press and stamp
The ball is rolled and pressed to a round shape and stamped with its markings.
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Weigh and measure
A major league ball must weigh between 5 and 5.25 ounces and be 9 to 9.25 inches around.
Worth repeating
- During World War II, rubber was banned for non-war goods in the US, so in 1943 baseballs got rubber-like balata shells instead.
- Benjamin Shibe, who invented the cork-centered baseball, patented it.
- In 2019 Major League Baseball officials said a lower seam profile had probably led to more home runs.
Back to the ground
Follow every input upstream and baseball starts as these 22 raw sources.
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Sources
Cite this page: "How baseballs are made." Assembly Line, 2026-11-03. https://assemblyline.org/make/baseball