Depends on their build, bone mass, muscle strength in their neck and shoulders, and other variables.
Quite frankly, I can't think of any good reason to ask this question to begin with. If there is a good reason, go to university and learn the math/physiology.
i am from america. i never took the time to learn what all the rest of the world uses for measurement. never understood why we aren't the same in that so confusing.