For smaller bones, a pressure of 25 pounds may be enough to break them. The amount of pressure that it would take to break a bone depends on the bone. Some bones are stronger than others.
There are many factors that would determine how many pounds of pressure it would take to break a bone, including the structure of the bone.
For a strong bone, such as a femur, it could take as much as 160 pounds of pressure to cause a fracture. This number can vary depending on different factors. Some of the factors include a person's age, how healthy he or she is, how strong a person's bones are, and how physically active he or she is.