How many punches can a guy take?

A quick, sharp blow that delivers some 3,300 newtons of force has a 25 percent chance of cracking an average person’s rib, she said. It takes more force to fracture the femur, Bir noted — maybe some 4,000 newtons — since that long thighbone is meant to support the body.

“That doesn’t means that below those values you won’t have a fracture or above them you will,” Bir said. The amount of damage a blow inflicts also varies due to factors such as the amount of muscle or fat covering a bone and the angle at which the blow lands, as well as the age and health of a person, which can affect bone strength.