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COR (Coefficient of Restitution)
Also known as: coefficient of restitution
COR measures how "lively" a softball is — the ratio of its rebound speed to its impact speed against a hard surface. A higher COR ball comes off the bat faster.
COR and compression together define how far a given ball will travel. Leagues specify a legal COR (commonly .44 or .52) alongside a compression limit so play stays safe and fair; mixing a hotter ball with a hot bat is what drives the equipment rules. COR is the ball-side companion to a bat’s BPF.
Example
A league mandates a .44 COR / 375-pound ball; a .52 COR ball from another league is illegal because it flies noticeably farther.
Related terms
- Compression RatingCompression rating measures how much force it takes to compress a softball a quarter inch, in pounds per square inch. A higher rating means a harder ball with more pop.
- BPF (Bat Performance Factor)BPF measures how much energy a bat returns to the ball compared with a completely rigid wall. A higher BPF means more "trampoline" pop off the barrel.
Related guides & benchmarks
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