The average length of an adult human's humerus bone is 14.4 inches. It is the longest bone of the entire arm, and it is analogous to and shorter than the femur in the leg.
The length of the humerus varies slightly by gender and by height. Forensic scientists can estimate total height based upon the length of the long bones of the body, including the humerus, if they know the gender of the person from whom the bones were collected. This is because the ratio between height and humerus length is a constant for adults of all genders. The constant for males is larger than for females.