How to Use ABI Calculator
Use ABI Calculator with systolic pressure readings from both arms and both ankles. Enter the four pressures in mmHg. The calculator uses the higher brachial pressure as the denominator for both ankles, then displays left ABI, right ABI, and average ABI.
If only one arm pressure is available, enter the same value for left and right arm. If ankle pressures are measured at multiple ankle arteries, use the pressure convention specified by your protocol or clinician.
Formula & Theory - ABI Calculator
The core calculation is:
ABI = ankle systolic pressure / highest brachial systolic pressureABI compares distal ankle pressure with central arm pressure. A low ratio suggests that pressure is dropping between the arm and ankle, which can happen with arterial narrowing or obstruction.
Very high ABI can also be abnormal because calcified or stiff arteries may not compress normally during cuff measurement. That is why the interpretation flags both low and high extremes.
Use Cases for ABI Calculator
Use it in vascular screening, diabetes foot-risk review, smoking-related vascular risk discussion, or follow-up after leg symptoms such as claudication.
It is also useful for teaching how peripheral arterial disease can be detected from simple pressure ratios rather than only from symptoms.