The Ankle-Brachial Index (ABI) measurement is a simple, noninvasive test that compares the blood pressure in your ankle with the blood pressure in your arm. Because blood pressure should normally be similar (or slightly higher) in the ankle than in the arm, this comparison helps evaluate how well blood is flowing to your legs and feet.

The ABI is most commonly used to check for peripheral artery disease (PAD), a condition in which the arteries that supply the legs become narrowed or blocked—usually from atherosclerosis (plaque buildup). Reduced blood flow can cause leg pain with walking and may increase the risk of slow-healing wounds, infections, and cardiovascular events.

During the test, a cuff is placed on your arm and on each ankle. A blood pressure reading is taken—often using a handheld Doppler ultrasound device to detect blood flow. The ABI is calculated by dividing the ankle systolic blood pressure by the arm (brachial) systolic blood pressure.

In plain language, ABI results generally mean:

• Normal blood flow: ABI is typically around 1.0 to 1.3, suggesting no significant blockage in the leg arteries.
• Lower-than-normal ABI: An ABI below ~0.9 suggests PAD; lower numbers generally indicate more significant narrowing and reduced circulation.
• Very high ABI: An ABI above ~1.3 may mean the arteries are stiff/calcified (common in diabetes or chronic kidney disease), which can make pressures seem falsely high. In this situation, a related test (such as a toe-brachial index) may be recommended.

Your clinician will interpret your ABI in the context of your symptoms, risk factors, and other cardiovascular tests. ABI can also be repeated over time to track whether PAD is stable, improving, or worsening.

An ABI test is often ordered when a clinician suspects peripheral artery disease or wants to assess circulation in the lower extremities. It may be done in a doctor’s office, vascular lab, or as part of cardiovascular risk evaluation.

Common symptoms that may prompt ABI testing include:

• Leg pain, cramping, heaviness, or fatigue with walking that improves with rest (intermittent claudication)
• Foot or toe pain at rest, especially at night, which may improve when the leg is lowered
• Cold feet, numbness, tingling, or weakness in the legs
• Non-healing sores/ulcers on the feet or lower legs
• Color changes in the feet (pale, bluish, or reddish) or shiny skin and hair loss on the legs
• Reduced or absent pulses in the feet noted on physical exam

It may also be recommended if you have risk factors that increase the likelihood of PAD and atherosclerosis, such as:

• Smoking (current or past)
• Diabetes
• High blood pressure
• High cholesterol
• Older age (risk increases with age)
• Family history of cardiovascular disease
• Chronic kidney disease

Beyond diagnosing PAD, ABI may be used to:

• Estimate cardiovascular risk, since PAD is linked with higher risk of heart attack and stroke
• Guide treatment decisions (exercise therapy, medications, referral to vascular specialists)
• Monitor response to treatment over time
• Evaluate circulation before or after certain procedures (e.g., vascular interventions)

• Peripheral artery disease (PAD) / peripheral arterial disease
• Atherosclerosis (plaque buildup in arteries)
• Critical limb ischemia / chronic limb-threatening ischemia
• Diabetic peripheral vascular disease
• Non-healing lower-extremity ulcers (including diabetic foot ulcers)
• Coronary artery disease (CAD)
• Cerebrovascular disease (stroke/TIA risk associated with systemic atherosclerosis)
• Arterial calcification/medial arterial sclerosis (often associated with diabetes or chronic kidney disease)

• Screening for and early detection of peripheral artery disease (PAD) in at-risk individuals
• Monitoring lower-extremity circulation and walking-related leg symptoms
• Reducing overall cardiovascular risk by identifying systemic atherosclerosis early
• Guiding lifestyle changes (smoking cessation, walking programs) and preventive care plans
• Supporting diabetes care by assessing blood flow to the feet and risk for ulcers
• Tracking treatment effectiveness for PAD (medications, supervised exercise therapy, or procedures)
• Promoting foot health and wound-healing readiness in people with poor circulation