Coefficient of Restitution (COR)

Coefficient of Restitution, or COR, measures how efficiently the clubface rebounds when it hits the golf ball.

It’s expressed as a number between 0 and 1. A higher COR means more energy is transferred from the club to the ball, which generally leads to higher ball speed. The USGA limits COR to keep equipment within fair performance standards, so manufacturers design faces to sit just below that threshold.

Fitters don’t adjust COR directly, but it’s an important part of how a driver or fairway wood performs.

Two clubs with the same loft and shaft can produce different results if one face is more efficient. Understanding COR helps explain why certain clubs feel “hotter” at impact and why off-center hits behave differently across models. It’s one of the core factors behind modern distance technology, especially in metalwoods.