What Should Ankle Blood Pressure Be? An Indicator of Health

Ankle blood pressure in a healthy person lying flat is typically about 10 to 20 mmHg higher than arm blood pressure on the systolic (top number) reading, with diastolic pressure roughly the same in both locations. But the raw ankle reading matters less than how it compares to the arm reading, a ratio known as the ankle-brachial index. That ratio, more than any single number, is what clinicians use to gauge vascular health and flag problems ranging from clogged leg arteries to stiffened blood vessels.

Why Ankle Pressure Is Naturally Higher Than Arm Pressure

If you have ever had blood pressure taken at your ankle and noticed it was higher than your usual arm reading, that is normal physiology at work. As blood travels away from the heart, pressure waves bounce off arterial branch points and walls, and those reflected waves amplify systolic pressure in the lower extremities. A large systematic review pooling data from multiple studies found that ankle systolic blood pressure, measured while lying down, averaged about 17 mmHg higher than arm blood pressure in the general population. Diastolic pressure, by contrast, showed essentially no difference between the two sites.¹ So if your arm reads 120/80, an ankle systolic reading somewhere around 130 to 140 while lying flat would be unremarkable.

This natural amplification is exactly why doctors do not just look at the ankle number in isolation. A “normal” ankle systolic reading of 135 mmHg in someone whose arm reads 120 carries a very different meaning than the same 135 in someone whose arm reads 160. The relationship between the two readings is what tells the story.

The Ankle-Brachial Index and What the Numbers Mean

The ankle-brachial index, or ABI, is calculated by dividing the systolic blood pressure at the ankle by the systolic blood pressure in the arm. Clinicians use a blood pressure cuff and a handheld Doppler probe to get these readings, and the standard method takes the highest systolic pressure at the ankle and the highest from either arm to compute the ratio.² Given the natural amplification described above, a healthy ABI lands somewhere between about 1.00 and 1.40. A value of 1.10, for example, means your ankle systolic pressure is 10% higher than your arm pressure, which is perfectly normal.

The clinically important threshold sits at 0.90. An ABI at or below that level is considered abnormal and is the widely accepted cutoff for diagnosing peripheral artery disease, a condition where narrowed arteries reduce blood flow to the legs.² In people with documented vascular disease, the pattern flips entirely: instead of being higher at the ankle, systolic pressure can be roughly 33 mmHg lower at the ankle compared to the arm, reflecting the blockages that choke off flow to the legs.¹

A simple way to think about it: an ABI near 1.10 means the plumbing between your heart and your ankles is open and working. An ABI below 0.90 means something along that route is partially blocked. And an ABI above about 1.40 raises a different concern, which we will get to shortly.

Low Ankle Pressure and Cardiovascular Risk

An ABI below 0.90 is not just a leg problem. The arterial narrowing that reduces ankle pressure is almost never limited to the legs alone. The same plaque-building process affects arteries throughout the body, including those feeding the heart and brain. This makes a low ABI one of the more reliable signals that cardiovascular disease is already underway.

Data from the large Atherosclerosis Risk in Communities study showed that people with an ABI below 0.90 were roughly twice as likely to have coronary heart disease and more than four times as likely to have experienced a stroke or transient ischemic attack compared to those with a normal ABI.³ The prevalence of preclinical plaque in the carotid arteries, the vessels supplying the brain, also increased steadily as ABI dropped. In other words, the ankle is acting as a window into what is happening at sites far from the feet.

Research in older adults has confirmed and extended these findings. In a study following older participants over time, those with a low ankle-arm index had significantly higher rates of coronary heart disease events even after accounting for traditional risk factors like diabetes, smoking, high cholesterol, and existing heart disease. The hazard ratio for coronary events was about 1.4 for those with a low ABI.⁴ That may sound modest, but when you consider that these individuals already had their conventional risks controlled for in the analysis, the added predictive value of the ankle measurement becomes clear.

When Ankle Pressure Is Too High

An ABI above roughly 1.40 is not a sign of extra-healthy arteries. It usually means the ankle arteries have become so stiff and calcified that the blood pressure cuff cannot compress them properly, producing artificially elevated readings. This medial arterial calcification is especially common in people with diabetes and chronic kidney disease.⁵

The danger here is twofold. First, a person could actually have significant artery blockages in their legs, but the calcification masks the low pressure that would normally show up as a reduced ABI. The ratio looks normal or even high when it should be low. Second, the arterial stiffness itself is a cardiovascular risk factor. The same study of older adults mentioned earlier found that people with noncompressible (very high ABI) arteries had hazard ratios of about 1.7 for coronary heart disease, higher even than those with a low ABI.⁴

Chronic kidney disease appears to amplify this problem. Research from the Cardiovascular Health Study found that the link between kidney disease and a high ABI was qualitatively stronger among people who also had diabetes, though small sample sizes in the high-ABI group limited statistical power.⁶ For anyone with diabetes, kidney disease, or both, a “normal-looking” ABI deserves some skepticism and may warrant additional testing.

The Toe-Brachial Index as a Workaround

When arterial calcification makes ankle readings unreliable, clinicians can measure pressure at the big toe instead. Toe arteries are smaller and tend to be spared from the wall calcification that plagues the larger ankle arteries. A toe-brachial index, or TBI, uses toe pressure divided by arm pressure to evaluate leg circulation in people where the standard ABI may be falsely elevated.⁷

A normal TBI is generally above 0.70, and a value below about 0.60 suggests peripheral artery disease. In people with type 2 diabetes, research has found that TBI had a sensitivity above 82% for detecting PAD confirmed by imaging, with specificity comparable to ABI in people without calcification.⁸ If you have diabetes and your doctor measures your ABI as perfectly normal but you have symptoms like calf pain when walking, asking about a TBI is reasonable.

How Ankle Pressure Is Measured

The traditional method involves lying flat for about ten minutes, then having a clinician place a blood pressure cuff just above the ankle and use a handheld Doppler ultrasound probe to listen for blood flow while inflating and deflating the cuff. The same is done on both arms. The whole process takes roughly nine minutes once you are positioned and rested.⁹ It requires some skill, and results can vary between technicians.

Automated oscillometric devices, similar to the digital blood pressure monitors many people own, have become increasingly available for ABI screening. These machines inflate cuffs on all four limbs simultaneously, which is faster and eliminates the operator-dependent variability of handheld Doppler. One validation study found 95% agreement between Doppler and oscillometric methods in diagnosing PAD, with the automated method achieving 83% sensitivity and 97% specificity at the standard 0.90 cutoff.⁹ Averaging two or three automated readings improved accuracy slightly. That said, broader reviews note that automated devices can be less reliable in people who already have low ankle pressures, exactly the population where accuracy matters most.¹⁰

In clinical practice, automated devices work well for initial screening in primary care and general populations, where most people will have normal values. For anyone whose results come back borderline or abnormal, the manual Doppler method remains the reference standard.

Position Matters

Standard ABI measurement assumes you are lying flat. That is not just convention; gravity significantly changes ankle pressure. When you sit up or stand, the column of blood between your heart and your feet adds hydrostatic pressure to the ankle reading. Early research on this found that departing from the horizontal position changed ankle pressure in ways fully explained by gravitational effects, and the body did not meaningfully compensate for the positional shift as long as the new posture was held.¹¹ Extreme bending of the hip and knee also reduced ankle pressure and pulse intensity, likely because of arterial kinking at the joint.

The practical takeaway is that ankle pressure readings taken while sitting or standing are not comparable to the lying-down values used to calculate ABI. If you have your blood pressure checked at the ankle during a routine visit and you are sitting on an exam table with your legs dangling, that number is not an ABI measurement. Proper measurement requires lying flat with legs at heart level.

Exercise and Post-Workout Drops

Ankle pressure behaves differently during and immediately after exercise, and this is actually used as a diagnostic tool. In someone with a borderline resting ABI, having them walk on a treadmill until symptoms appear and then retesting can unmask blockages that are not severe enough to show at rest. A significant drop in ankle pressure after exercise suggests that narrowed arteries cannot deliver enough blood flow to meet the increased demand.

What surprises many people, including some clinicians, is that ankle pressure can drop substantially after hard exercise even in perfectly healthy young individuals. A study of healthy young participants found that over 60% experienced a post-exercise decrease in ABI greater than 20%, and none of them had any arterial turbulence or structural abnormality on ultrasound.¹² The researchers concluded that a 20% ABI drop after exercise appears to be a normal physiological response in young people, not necessarily evidence of disease. This is worth knowing if you are young, active, and sent for exercise ABI testing: a post-exercise dip alone does not mean you have peripheral artery disease.

For post-exercise testing, timing matters. Automated devices have a practical edge here because they can capture ankle and arm pressures nearly simultaneously, whereas manual Doppler requires measuring each limb sequentially. Research comparing the two methods after heavy exercise found that automated measurements were available about 14 seconds faster on average, with high correlation between the two approaches and slightly less test-to-test variability with the automated method.¹³

Comparing Left and Right Sides

A discrepancy between the two ankles, or between one ankle and one arm, carries its own diagnostic meaning beyond what the ABI alone reveals. An inter-leg systolic blood pressure difference greater than about 15 to 20 mmHg has been linked to increased cardiovascular risk and may point to disease that is worse on one side.¹⁴

A study of elderly Chinese adults went further, examining what happens when you combine inter-arm differences, inter-leg differences, and ABI all together. Participants with two or more abnormal inter-limb measures had about 50% higher risk of future cardiovascular events compared to those with no abnormalities, even after adjusting for other risk factors.¹⁵ One abnormal measure raised risk too, though not quite to statistical significance. The picture that emerges is that asymmetry in blood pressure across the limbs is itself a marker of widespread vascular trouble.

Should Everyone Be Screened?

Given how informative the ABI can be, you might expect that routine screening is recommended for all adults. It is not. The U.S. Preventive Services Task Force concluded that current evidence is insufficient to determine whether screening asymptomatic adults with ABI improves outcomes enough to justify widespread testing.¹⁶ The concern is not that the test is inaccurate. It is that detecting peripheral artery disease in someone without symptoms may not change their treatment in a meaningful way, since the management for early PAD, such as exercise, smoking cessation, cholesterol control, and blood pressure management, largely overlaps with what those individuals should already be doing for general cardiovascular health.

Where ABI testing clearly earns its keep is in people who have symptoms (leg pain with walking, non-healing foot wounds, or unexplained leg fatigue) and in populations at elevated risk, particularly people over 65, smokers, and those with diabetes. In those groups, an abnormal ABI may tip the scales toward more aggressive medication, referral to a vascular specialist, or supervised exercise therapy.

Can You Improve a Low Ankle Blood Pressure?

If you have been diagnosed with peripheral artery disease based on a low ABI, structured walking programs are one of the most effective non-surgical interventions. An observational study of patients with claudication (the cramping leg pain that comes with walking when arteries are narrowed) found that a pain-free walking program improved ABI by an average of 0.07 points, with improvements measurable after just five weeks of slow walking. Six-minute walk distance and pain-free walking distance both increased substantially as well.¹⁷ An improvement of 0.07 may sound small, but on the ABI scale it represents a meaningful shift in leg circulation.

Foot exercises have also shown promise in smaller studies. Research in young adults at risk for PAD found that a simple foot exercise regimen raised the average ABI from 0.75, which is in the abnormal range, to 0.97, which is normal.¹⁸ That is a striking shift, though this was a small study and the mechanism likely involves improved arterial compliance and blood flow rather than reversal of established plaque. For people with mild reductions, the evidence suggests that targeted physical activity can make a real difference.

Ankle Pressure in Children and Infants

ABI values that would alarm a clinician in an adult can be perfectly normal in a newborn. Research measuring ABI in neonates and infants found that the normative ABI in this age group is significantly lower than in older children and adults. The ratio gradually rises during the first two years of life, reaching adult-equivalent values by around the second birthday.¹⁹ This matters clinically because applying the adult 0.90 cutoff to a baby would lead to false diagnoses. Pediatric vascular assessment requires age-appropriate reference ranges, which are less well established than adult norms.

By later childhood and adolescence, ABI values are generally comparable to adult ranges, and the same interpretive thresholds apply. Outside of congenital heart defects or aortic anomalies, a low ABI in a child or teenager is uncommon and warrants investigation for unusual vascular conditions rather than the atherosclerosis-driven narrowing typical in older adults.