The heel bone is called the calcaneus. It is the largest and strongest bone in your foot, measuring roughly 75 to 89 millimeters from front to back. The calcaneus sits at the very back and bottom of the foot, just below the ankle bone (the talus), and serves as the foundation that transfers your full body weight to the ground every time you take a step.
What the Calcaneus Does
The calcaneus has two main jobs. First, it acts as a weight-bearing platform. When you stand, walk, or run, the force of your body travels down through your leg, passes through the ankle bone, and lands on the calcaneus before reaching the ground. Second, it works as a lever for your calf muscles. The Achilles tendon, the thick cord running down the back of your lower leg, attaches directly to a rough, textured area on the back surface of the calcaneus. When your calf muscles contract, they pull on this attachment point to push your foot downward, powering every step, jump, and push-off.
The underside of the calcaneus also anchors the plantar fascia, the tough band of tissue that runs along the sole of your foot and supports your arch. This means the heel bone is essentially the anchor point connecting your leg’s pushing power above to your foot’s structural support below.
Where It Sits Among the Foot Bones
The calcaneus is one of seven tarsal bones that make up the rear and midfoot. It connects to the talus (ankle bone) above it, forming the subtalar joint. This joint is what allows your foot to roll inward and outward on uneven surfaces. The calcaneus also connects to the cuboid bone in front of it, forming the calcaneocuboid joint, which contributes to the flexibility of your midfoot.
Together, these joints let the calcaneus do more than just absorb impact. They allow your foot to adapt its shape as you walk across different terrain, shifting between a flexible shock absorber at heel strike and a rigid lever when you push off.
Surface Landmarks of the Calcaneus
Despite looking like a simple block of bone, the calcaneus has a surprisingly complex surface. The top rear portion has a smooth articular facet where it meets the talus. The back surface is divided into zones: a smooth upper area where a fluid-filled cushion (bursa) sits, and a rougher middle area where the Achilles tendon attaches.
On the inner side, a shelf-like projection called the sustentaculum tali juts out to help support the talus from below. The outer surface has several small bony ridges that serve as guide rails for tendons running along the outside of the ankle. On the bottom, two bony bumps called the medial and lateral processes of the calcaneal tuberosity are the parts of your heel that actually contact the ground when you stand.
Common Heel Bone Problems
Heel Spurs
A calcaneal spur is a small, pointed growth of extra bone that develops on the underside of the calcaneus, typically where the plantar fascia attaches. Heel spurs show up in roughly 11% to 21% of people in young to middle-aged populations. Many people with heel spurs have no pain at all and only discover them on an X-ray taken for another reason. When pain does occur, it usually comes from inflammation of the surrounding soft tissue rather than the spur itself.
Calcaneal Fractures
Because the calcaneus bears so much force, it can fracture during high-impact events like falls from a height or car accidents. About 75% of calcaneal fractures involve the joint surface where the calcaneus meets the talus. These intra-articular fractures are graded using a system called the Sanders classification, which looks at how many fragments the bone has broken into and where the fracture lines cross the joint. The severity of the fracture on this scale helps determine whether surgery is needed, though the best approach for many of these fractures remains debated even among specialists.
Sever’s Disease in Children
In growing kids, the calcaneus has a growth plate at its back end that hasn’t yet fused with the rest of the bone. Repetitive stress from running and jumping can irritate this growth plate, causing heel pain known as Sever’s disease (calcaneal apophysitis). It is one of the most common causes of heel pain in active children and adolescents. A doctor typically diagnoses it by pressing on the heel and watching the child move. Most kids recover within a few weeks to months with rest and activity modification.
Why the Calcaneus Matters for Everyday Movement
Your calcaneus is the first bone to hit the ground with every step you take. It absorbs the initial shock of heel strike, transfers force forward through the midfoot as you roll through your stride, and then acts as a rigid lever arm when your calf muscles fire to propel you forward. A healthy calcaneus handles forces of two to three times your body weight during normal walking, and significantly more during running or jumping. That combination of size, density, and strategic positioning makes it arguably the most mechanically important bone in the foot.