CoverTwo pieces of leather, sewn together round the ball.
StitchesThread sewn by hand through both pieces of the cover.
SeamThe line where the two cover pieces meet.
Cover pieceOne of two matching pieces. Each wraps half the ball.
Cut in half 4
Cork center (core)A small ball of cork and rubber at the middle.
Yarn windingsYarn wound tight round the middle, layer on layer.
Inner rubber layerRubber molded straight onto the cork.
Outer rubber layerA thinner coat of rubber over the first.
How this list was compiled: Every name checked on 2026-09-30 and kept only where at least two of these use it. (1) Wikipedia, Baseball (ball), https://en.wikipedia.org/wiki/Baseball_(ball) : a rubber or cork center wound with yarn under a cover of horsehide or cowhide; the cover is two saddle-shaped pieces stitched together, 108 stitches; the cork core surrounded by black rubber, then a layer of red rubber; the seams. (2) How Products Are Made, Baseball, https://www.madehow.com/Volume-1/Baseball.html : three basic parts, the cushioned cork center, the wool and poly/cotton windings and the cowhide cover; the cork is encased in a black inner and a red outer layer of rubber; the cover is two figure-8 pieces sewn by hand with 108 stitches. (3) US Patent 932,911, Base-ball (1909), https://patents.google.com/patent/US932911A/en : a cork center in a rubber shell, layers of yarn wound on it, an outer cover of horsehide stitched on. (4) US Patent 2,358,535, Method of making baseballs (1944), https://patents.google.com/patent/US2358535A/en : core, cover, and the seam on the surface of the ball. Licence: own work
The drawing: Own drawing from plain geometry; nothing traced. Licence: own work
How it works
A baseball has three main parts: a small cork center wrapped in rubber, yarn wound round it, and a leather cover sewn on. The first drawing shows the outside, the second a ball cut in half.
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The outside
The cover is two matching pieces of leather, each shaped like a figure 8. They meet along one long seam that curves round the ball, and stitches of waxed thread hold them together.
The inside
At the middle is the cork center. Two layers of rubber are molded onto it, the outer one thinner. Yarn is wound tight over the rubber, and it fills most of the ball.
Questions and answers
What are the parts of a baseball?
From the middle out: the cork center, an inner and an outer layer of rubber, the yarn windings and the leather cover. The cover is two pieces joined at the seam by stitches.
What is inside a baseball?
A small ball of cork and rubber, coated in two layers of rubber, with yarn wound tightly round it. Most of the yarn is wool. The windings make up most of what is inside.
How many stitches are on a baseball?
A regulation baseball has 108 stitches. They are sewn by hand and join the two pieces of the cover along the seam.
What is the cover of a baseball made of?
Leather. Top-level balls were covered in horsehide until 1974 and have been covered in cowhide since. Some cheaper balls have a synthetic cover.