What is the largest bone in the human body?

The femur, or thigh bone, is the largest, longest and strongest bone in the human body. In adults it’s typically about 45–50 cm (18–20 in) long, roughly a quarter of a person’s height. It runs from the hip to the knee and supports the body’s weight when standing, walking and running.

Largest Bone in the Human Body: The Femur (Thigh Bone)

General information only. This article explains the basics and is not medical advice. For anything about your own health, talk to a doctor or other qualified professional.

How strong is the femur?

The femur is remarkably tough. Its hollow, tube-like shaft gives it strength without too much weight, like a scaffolding pole. It can withstand forces of several times body weight during everyday activities such as running and jumping, and breaking it usually takes a major impact, such as a car accident.

Where it connects

End	Joint	Connects to
Top (head of the femur)	Hip joint, a ball-and-socket	Pelvis
Bottom	Knee joint	Tibia (shinbone) and kneecap

The kneecap sits in front of the knee joint; see what the kneecap is called.

Largest vs smallest bones

Bone	Where	Size
Femur	Thigh	About 48 cm
Tibia	Shin	About 43 cm
Fibula	Lower leg	About 40 cm
Humerus	Upper arm	About 36 cm
Stapes	Middle ear	About 3 mm; see the smallest bone

Bones by the numbers

Adults have 206 bones. Babies are born with about 270, which fuse together as they grow.
More than half of your bones are in your hands and feet.
Bones are living tissue: they constantly rebuild themselves, and the inside of the femur contains marrow that makes blood cells.

Femurs in science

Because the femur is proportional to height, forensic scientists and archaeologists can estimate how tall a person was from this one bone. Femur fossils have helped show when human ancestors began walking upright.

The strongest muscle

The femur is surrounded by powerful muscles, including the quadriceps and hamstrings. For the strongest muscle of all, see the strongest muscle in the human body.