ABI Calculator (Ankle-Brachial Index)

The ABI is a simple, non-invasive ratio that compares the systolic blood pressure at the ankle to the systolic blood pressure at the arm (brachial artery). It is used as a quick screening tool to detect peripheral artery disease (PAD), a condition where narrowed arteries reduce blood flow to the limbs. A normal ABI falls between 1.0 and 1.4.

To calculate the ABI, divide the highest systolic ankle pressure (either dorsalis pedis or posterior tibial) on a given side by the highest systolic brachial pressure from either arm. For example, if your highest right ankle pressure is 132 mmHg and your highest brachial pressure is 122 mmHg, your right ABI is 132 ÷ 122 ≈ 1.08.

An ABI above 1.4 suggests non-compressible, calcified vessels. Values between 1.0 and 1.4 are considered normal. An ABI of 0.91–0.99 is borderline, while 0.71–0.90 indicates mild PAD, 0.41–0.70 indicates moderate PAD, and values at or below 0.40 indicate severe PAD requiring urgent evaluation.

The ABI test is recommended for all patients over 70 years of age, and for patients over 50 who smoke or have diabetes. It is also used to evaluate leg pain during walking (claudication), non-healing wounds on the feet, or to assess cardiovascular risk in patients with known artery disease.

The ABI test can be performed by trained healthcare professionals including physicians, nurses, and vascular technicians. It requires a blood pressure cuff and a Doppler ultrasound device to accurately detect ankle pulse signals. While the test itself is non-invasive, the results should always be interpreted by a qualified clinician.

An ABI greater than 1.4 indicates that the arteries may be stiff and non-compressible, which commonly occurs in patients with diabetes or advanced age due to arterial calcification. This result can actually mask underlying PAD, and further vascular testing such as a toe-brachial index (TBI) is typically recommended.

No. This calculator is intended for educational and screening purposes only. While the ABI test is a well-validated clinical tool, this online calculator cannot replace a proper medical examination, professional Doppler measurement, or physician assessment. Always consult a healthcare provider if you have concerns about peripheral artery disease or cardiovascular health.

Your left ABI would be 110 ÷ 120 ≈ 0.92, which falls in the borderline range (0.91–0.99). This may warrant monitoring and follow-up with a physician, especially if you have risk factors such as smoking, diabetes, or hypertension.