Heel spurs develop when calcium deposits slowly build up on the underside of your heel bone, a process that typically takes many months of repeated stress. They form because the muscles and connective tissue attached to your heel are under chronic tension, and your body responds by laying down extra bone at the attachment point. About 15 to 25% of the general population has heel spurs without ever knowing it, which means the spur itself isn’t always the problem.
How a Heel Spur Actually Forms
The underside of your heel bone is an anchor point. Your plantar fascia (the thick band of tissue running along the bottom of your foot) attaches there, along with several smaller muscles that help control your toes and stabilize your arch. Every time you take a step, these structures pull on the heel bone. Under normal conditions, the bone handles this just fine.
When the pulling becomes excessive or prolonged, the story changes. Your body interprets that constant tug as a signal that the bone needs reinforcement. It starts depositing calcium at the spot where the tissue connects to the bone. Over months, those deposits accumulate into a bony growth, sometimes shaped like a small hook or shelf extending forward from the heel. The spur itself can reach several millimeters in length, though size varies widely from person to person.
This is why heel spurs and plantar fasciitis are so closely linked. Roughly 80% of people with plantar fasciitis also have a heel spur. The inflamed, overworked fascia creates the exact kind of sustained tension that triggers calcium buildup. Longer spurs tend to correlate with more pain and worse foot function, and the longer someone has had symptoms, the larger the spur tends to grow.
The Biggest Risk Factor: How Your Foot Moves
Abnormal foot mechanics, particularly excessive pronation (when your foot rolls inward too far with each step), is considered the primary driver of heel spur formation. When you overpronate, the plantar fascia and the muscles attached to your heel bone are stretched and pulled at angles they aren’t designed for. That abnormal tension concentrates force at the heel attachment point, accelerating calcium deposits over time.
Both flat feet and high arches can contribute to this problem. Flat feet tend to overpronate naturally, while high arches create a rigid foot that absorbs shock poorly, transferring more impact directly to the heel. Either pattern puts extra mechanical load on the same vulnerable spot.
Body Weight and Age
Carrying extra weight meaningfully increases your risk. People with heel pain have a significantly higher average BMI (around 30) compared to those without it (around 28). Research suggests that in non-athletes, BMI plays a greater role in heel pain than foot structure alone. Every pound of body weight translates to several pounds of force on your heel during walking, and even more during running or jumping. That cumulative load speeds up the process of calcium deposition.
Age matters too. Spur length correlates significantly with age, likely because older adults have had more years of repetitive stress on the heel and because the plantar fascia loses elasticity over time, becoming less capable of absorbing force without transferring it to the bone.
Activities and Surfaces That Contribute
Frequently walking, running, or jumping on hard surfaces wears down the heel and increases the strain on the plantar fascia. Concrete floors, pavement, and hard gym surfaces are common culprits. People whose jobs keep them on their feet for extended periods on hard flooring, such as warehouse workers, nurses, teachers, and retail employees, face higher risk simply because of accumulated hours of impact.
Prolonged standing, even without much walking, also shows an association with heel pain. When you stand in place, the plantar fascia is under constant low-grade tension without the relief that comes from sitting or shifting positions. Over years, that steady pull contributes to the same calcium buildup that more intense activity causes.
Shoes That Help and Hurt
Completely flat shoes, like basic flip-flops or ballet flats, force the heel to absorb more load because there’s no elevation to shift some of your weight forward. This increases tension on the plantar fascia. Very high heels create their own problems by distorting foot mechanics and concentrating pressure in unnatural ways, while narrow-toed shoes compress the foot and alter how forces distribute across the sole.
The ideal shoe for protecting your heel has a sole that absorbs shock, enough room for your foot to sit comfortably, and a heel that’s slightly elevated above the forefoot. This modest elevation reduces the pulling force on the plantar fascia without introducing the instability that comes with a high heel. If you spend your workday in dress shoes, switching to supportive walking shoes for your commute makes a real difference over time.
Why You Might Have One and Not Know It
Heel spurs show up on X-rays in 10 to 63% of people who have zero symptoms, depending on the population studied. A more consistent estimate puts asymptomatic spurs at 15 to 25% of the general population. This means the spur itself is not automatically painful. Many people walk around for years with bony growths on their heels and never feel a thing.
Pain tends to arise from the soft tissue inflammation surrounding the spur rather than the spur poking into your foot. When the plantar fascia or nearby tissues are irritated and swollen, the spur becomes a focal point for discomfort during weight-bearing. This is why two people with identical-looking spurs on an X-ray can have completely different experiences: one with debilitating morning heel pain, the other with none at all.
How Heel Spurs Are Found
Because spurs develop silently over months, most people don’t discover them until they seek help for heel pain. A standard foot X-ray is the primary way to confirm a spur’s presence. The spur appears as a white, bony projection extending from the bottom of the heel bone. Only about half of people with heel pain symptoms will actually show a visible spur on X-ray, which reinforces that the pain and the spur are related but separate issues.
Doctors look at the spur’s length, base width, and overall shape. Broad-based spurs with irregular, “fluffy” edges can sometimes indicate an inflammatory condition like psoriatic arthritis rather than simple mechanical wear. A thin, well-defined spur is more typical of the gradual calcium buildup caused by chronic strain. These distinctions help determine whether the spur is a standalone mechanical problem or a sign of something systemic.
Reducing Your Risk
Since heel spurs are the end result of months or years of excessive strain, prevention comes down to reducing that strain before it accumulates. Maintaining a healthy weight removes one of the most significant modifiable risk factors. Wearing supportive, shock-absorbing shoes, especially if you spend long hours on hard surfaces, protects the heel from repetitive impact. Orthotics or arch supports can correct overpronation and redistribute forces more evenly across the foot.
Keeping your calves and feet flexible also matters. Limited ankle flexibility (specifically, reduced ability to pull your toes toward your shin) is associated with heel pain. Regular calf stretches and foot mobility exercises help the plantar fascia and surrounding muscles absorb force more efficiently, reducing the traction on the heel bone that drives spur formation in the first place.