How to Take Blood Pressure on the Leg

Measuring blood pressure on the leg follows the same basic principle as an arm reading: you wrap an appropriately sized cuff around the limb, position it over an artery, and inflate until you can detect the pressure at which blood flow resumes. The technique matters most in situations where arm readings are unavailable or unreliable, or when comparing arm and leg pressures reveals problems like blocked arteries or a narrowed aorta. The details of cuff placement, patient positioning, and interpretation differ enough from a standard arm reading that getting them wrong can produce misleading numbers.

When and Why You Would Measure Blood Pressure on the Leg

Most people have their blood pressure checked on the upper arm, and that remains the standard. Leg measurement enters the picture in a few specific clinical scenarios. The British and Irish Hypertension Society identifies three main reasons: diagnosing coarctation of the aorta (a congenital narrowing that causes high pressure in the arms relative to the legs), screening for peripheral arterial disease, and situations where both arms are unavailable for measurement because of congenital malformations, dialysis fistulae, or lymph node removal after surgery.¹

The most common of these is screening for peripheral arterial disease, where fatty deposits narrow the arteries supplying the legs. In that case, the point is not simply to get a blood pressure number but to compare leg pressure with arm pressure, producing a ratio called the ankle-brachial index. If leg pressure is suspiciously low compared to the arm, it signals that blood flow to the lower limbs is compromised.

Where to Place the Cuff

There are two main sites: the ankle and the thigh. Each has its own purpose and its own quirks.

For an ankle reading, the cuff goes around the lower leg just above the ankle bones (the malleoli), with the bladder centered over either the posterior tibial artery (behind the inner ankle bone) or the dorsalis pedis artery (on top of the foot). In practice, clinicians often check both arteries and use the higher of the two systolic readings. This is the standard approach for calculating the ankle-brachial index.

For a thigh reading, a larger cuff wraps around the mid-thigh. This site is used less frequently but can help localize where a blockage sits along the leg’s arterial tree. Segmental limb pressure testing, first described in the 1950s, places cuffs at multiple levels (high thigh, above the knee, below the knee, and ankle) to map where pressure drops occur along the leg.² A sharp pressure drop between two adjacent cuffs points to a narrowing in that segment.

Cuff Size Matters More Than You Think

An arm cuff will not work on a thigh, and even ankle cuffs come in different sizes. The general rule is the same as for the arm: the inflatable bladder inside the cuff should encircle at least 80 percent of the limb’s circumference. A cuff that is too small produces falsely high readings; one that is too large reads falsely low.

Thighs are wider than upper arms, so a dedicated large-adult or thigh cuff is essential. Early researchers discovered this the hard way: when a narrow cuff (about 10 cm wide) was used on the thigh, it produced artificially elevated pressures, though this artifact actually helped identify blockages higher up in the aortoiliac region.² For a standard ankle reading, an adult arm cuff often fits well because the ankle circumference in most adults is similar to the upper arm. But in larger patients or when measuring the calf, you may need to size up.

Patient Positioning and Practical Steps

Position is important because gravity directly influences blood pressure in the legs. When you stand, blood in the lower limbs is subject to the weight of the column of blood above it, which pushes pressure readings higher. Research has confirmed that most of the increase in thigh blood pressure during standing comes from this hydrostatic effect, and that elevating a limb above the level of the heart causes pressure to drop.³

For a standard ankle-brachial index measurement, the patient lies flat on their back (supine) so that both the arm and the ankle are at roughly the same height, at the level of the heart. This removes the hydrostatic variable and makes the arm-to-leg comparison valid. Let the patient rest for five to ten minutes before starting, just as you would for an arm reading. If the patient cannot lie flat, note the position used, because sitting or standing will shift the numbers.

A step-by-step approach for the most common scenario, an ankle reading for the ankle-brachial index:

Rest period: Have the patient lie supine for at least five minutes with legs uncrossed.
Arm reading first: Measure systolic blood pressure in both arms. Record the higher value.
Apply the ankle cuff: Wrap an appropriately sized cuff around the lower leg just above the malleoli.
Locate the pulse: Find either the posterior tibial pulse (behind the inner ankle) or the dorsalis pedis pulse (on the top of the foot) with a handheld Doppler probe or by palpation.
Inflate and deflate: Inflate the cuff until the Doppler signal or pulse disappears, then slowly deflate. The pressure at which the signal returns is the systolic ankle pressure.
Repeat on the other side: Check both ankles.
Calculate: Divide the higher ankle systolic pressure by the higher arm systolic pressure to get the ABI.

Repeating the measurement and averaging two or three readings improves accuracy. One validation study found that averaging two oscillometric readings brought the difference from the Doppler reference down to about 0.02, compared to 0.03 for a single reading.⁴

Why Leg Blood Pressure Is Normally Higher Than Arm Blood Pressure

If you measure a healthy person’s blood pressure in both the arm and the leg under identical conditions, the leg reading is usually higher. Systolic pressure in the leg typically exceeds the arm by 10 to 20 mmHg. This is not a sign of a problem; it is normal physiology. The arteries in the legs are farther from the heart and run through larger muscle masses, and pulse-wave amplification (the way the pressure wave bounces and reinforces itself in stiffer, more peripheral vessels) pushes the peak systolic value up.

Research going back decades has confirmed that both systolic and diastolic pressures run higher in the legs than in the arms in healthy people, as well as in those with hypertension, various forms of heart disease, and thyroid conditions.⁵ The practical takeaway: a leg reading that is slightly higher than the arm does not mean high blood pressure. You need to interpret it against arm readings, not in isolation.

The Ankle-Brachial Index and What It Tells You

The ankle-brachial index is the single most useful number to come out of a leg blood pressure measurement. It is simply the ratio of ankle systolic pressure to arm systolic pressure. In a healthy person, that ratio is typically between 1.0 and 1.4, reflecting the normal tendency for leg pressure to be equal to or higher than arm pressure.

An ABI below 0.9 is generally considered diagnostic of peripheral arterial disease, meaning the arteries supplying the legs are significantly narrowed. The lower the number, the more severe the disease. Values between 0.4 and 0.9 suggest moderate disease, while anything below 0.4 raises concern about critical limb ischemia, where blood flow is so restricted that tissue damage becomes a risk.

On the other end of the scale, an ABI above 1.4 can also be abnormal. It often indicates that the arterial walls have become stiff and calcified, particularly in people with diabetes or advanced kidney disease. The calcified arteries resist compression by the cuff, so the cuff has to be inflated to an artificially high pressure before it collapses the vessel, producing a falsely elevated reading. An ABI above 1.3 in the presence of medial arterial calcification has been linked to increased cardiovascular mortality.⁶

Doppler Versus Oscillometric Devices

The traditional gold standard for ankle pressure uses a handheld continuous-wave Doppler ultrasound probe. You hold the probe over the artery at the ankle, inflate the cuff, then slowly deflate it while listening for the return of the Doppler signal. This gives you a systolic pressure reading and is considered the reference method for calculating the ABI.

Oscillometric devices are the automated blood pressure monitors found in most clinics and hospitals. They detect pressure oscillations within the cuff itself rather than relying on an external Doppler signal. They are faster and easier to use: one validation study found that automated oscillometric ABI measurement took about six minutes on average, compared to about nine minutes for the Doppler method.⁴ The same study found that oscillometric and Doppler methods agreed on the diagnosis of peripheral arterial disease in about 95 percent of cases.

That said, the oscillometric method has a known limitation: in patients with blockages in the smaller arteries of the lower leg (the crural arteries), oscillometric readings can overestimate the true pressure. A study comparing the two methods in patients with confirmed arterial disease found a high overall correlation, but noted that several patients with crural artery blockages had oscillometric pressures that were higher than the Doppler-derived values.⁷ If you are screening a general population for peripheral arterial disease, an oscillometric device is a reasonable and practical choice. If you already know a patient has lower-leg arterial disease and need a precise reading, Doppler remains the better tool.

When Leg Readings Can Mislead You

Arterial calcification is the biggest confounder when measuring blood pressure on the leg. People with diabetes, chronic kidney disease, or advanced age are prone to calcium deposits building up in the walls of their leg arteries, making the vessels rigid. A stiff artery does not compress easily under the cuff, so the cuff registers a higher pressure than what is actually inside the vessel. This pushes the ABI reading upward, potentially masking underlying peripheral arterial disease.

Research confirms that an elevated ABI, while statistically associated with the presence of medial arterial calcification, is a poor diagnostic test for it. One study found that sensitivity was only about 16 percent, meaning the vast majority of patients with calcification did not have an elevated ABI.⁸ In practice, this means you cannot rely on the ABI alone to tell you whether calcification is present. If a patient has risk factors for calcification and an unexpectedly normal or high ABI, additional testing (like a toe-brachial index, which uses the smaller, less calcified digital arteries) may be needed.

Obesity can also complicate leg measurements. A very large thigh or calf makes cuff fitting difficult, and excess soft tissue between the cuff and the artery can dampen the signal. In these cases, the ankle is generally easier to work with than the thigh, because there is less soft tissue at the ankle level.

Screening for Coarctation of the Aorta

Coarctation of the aorta is a congenital narrowing of the large artery leaving the heart. It typically occurs just past the point where the arteries to the arms branch off, which means blood pressure in the arms is elevated while pressure in the legs is reduced. Comparing arm and leg blood pressure is one of the simplest ways to detect this condition. A systolic pressure in the legs that is lower than in the arms, rather than the expected 10-to-20 mmHg higher, raises a red flag.

The comparison is useful even after surgical repair. Research on post-operative coarctation patients found that those with a residual pressure gradient between the upper and lower extremities showed a widening of that gradient during sleep, while patients whose repair was complete had matching pressure profiles in both the arms and legs throughout the day.⁹ This suggests that monitoring the arm-leg pressure difference over time can help detect whether a repair is holding or if re-narrowing is developing.

Leg Blood Pressure in the Operating Room and ICU

In surgery and critical care, the arms are not always accessible. One arm might be tucked at the patient’s side, the other connected to an arterial line or intravenous access. In these situations, wrapping a blood pressure cuff around the ankle or calf becomes a pragmatic workaround. But the readings behave differently under anesthesia.

A study of patients under general anesthesia in the lateral position (lying on their side) found that ankle blood pressure readings were not interchangeable with simultaneous invasive arterial measurements. However, the researchers identified useful clinical thresholds: an ankle mean arterial pressure above 86 mmHg could rule out hypotension with 99 percent accuracy, and an ankle systolic pressure below 144 mmHg could rule out hypertension with 95 percent accuracy.¹⁰ So while the exact numbers may not match, the ankle reading can still function as a reliable screening tool for dangerous pressure swings during surgery.

In the intensive care unit, sepsis and vasopressor medications add another layer of complexity. Blood pressure measured at the femoral artery (in the leg) and the radial artery (in the arm) do not always agree. One study of septic patients on norepinephrine found that about three-quarters of paired measurements showed a gradient of at least 5 mmHg between the two sites. Interestingly, the dose of norepinephrine did not influence the size of this gap, and the researchers concluded that femoral and radial measurements were clinically interchangeable for most septic patients.¹¹ Still, knowing that a small gradient is common prevents overreacting to a modest difference between the two sites.

Doing It at Home

Home blood pressure monitoring on the leg is less common than arm monitoring, partly because validated home devices are designed for the upper arm. If your healthcare provider has asked you to track leg blood pressure at home, usually because your arms are not usable, the key principles carry over from the clinical setting: use a cuff that fits the limb properly, lie down so the cuff is level with your heart, rest for at least five minutes before measuring, and take two or three readings spaced a minute apart.

Consumer oscillometric monitors can technically be placed at the ankle, but most have not been specifically validated for that site. If you need a home ankle-brachial index for ongoing peripheral arterial disease monitoring, ask your clinician which device they recommend. Some professional-grade oscillometric devices that measure arm and ankle pressures simultaneously have been validated and shown to agree with Doppler in the vast majority of cases.⁴ A standard wrist monitor or finger monitor is not suitable for this purpose.

If you are checking your own legs because you are curious about peripheral arterial disease, keep in mind that a single home reading is not a diagnosis. The ABI needs to be interpreted alongside your symptoms, risk factors, and potentially a Doppler study if the initial screen is borderline. A consistent ABI below 0.9 on repeated testing is the point at which you and your doctor should discuss further evaluation.