What is the longest bone in the human body?

The longest bone in the human body is the femur.

The femur is the single bone in each upper leg, extending from the hip to the knee. Its length, thickness, and shape help support the body's weight and transfer force during walking, running, and jumping. On average, the femur accounts for roughly 27% of a person's height, although proportions vary between individuals.

The femur is also among the body's strongest bones. Its rounded head fits into the hip socket, while its lower end forms part of the knee joint with the tibia. The bone is built to withstand substantial compressive and bending forces, though high-impact injuries can still fracture it.

A common mix-up is confusing the femur with the tibia, the larger lower-leg bone. The tibia is important for weight-bearing, but it is considerably shorter. The humerus, the upper-arm bone, is also long but does not exceed the femur.