ABI Calculator
Calculate right and left ankle-brachial index from arm and ankle systolic pressures with PAD interpretation.
Calculate Ankle Brachial Index
The ankle brachial index (ABI) compares systolic blood pressure at the ankle with systolic pressure at the arm. It is a simple screen for peripheral artery disease (PAD). Enter the highest arm pressure and the highest ankle pressures from each leg to get right, left, and overall ABI values with interpretation guidance.
ABI Formula
$$ABI = \dfrac{\text{ankle systolic pressure}}{\text{arm systolic pressure}}$$
Use the higher of dorsalis pedis or posterior tibial readings for each ankle, and the higher of the two arms for the denominator. The lower ABI between legs is often reported clinically.
Reading Your Results
Values from 1.0 to 1.4 are generally normal. Values below 0.9 suggest possible arterial narrowing. Very high ABI above 1.4 may reflect non compressible calcified vessels, especially in diabetes or chronic kidney disease. Combine ABI with symptoms such as leg pain during walking. For cardiovascular risk context, see the BMI Calculator and Max Heart Rate Calculator.
Frequently Asked Questions
What is a normal ankle brachial index?
ABI between 1.0 and 1.4 is usually considered normal. Values from 0.9 to 1.0 are often labeled borderline acceptable depending on clinical context.
Which ankle pressure should I use?
Record dorsalis pedis and posterior tibial pressures in each foot and use the higher value for that leg when calculating ABI.
What does ABI below 0.9 mean?
It suggests possible peripheral artery disease and warrants further vascular evaluation, especially when paired with exertional leg symptoms.
Why can ABI be greater than 1.4?
Stiff, calcified arteries may not compress normally during measurement, producing falsely elevated ABI readings. Specialized toe pressure testing may be needed.
Should I use the right or left ABI clinically?
Clinicians usually report the lower of the two leg values because the worst perfused limb drives symptom burden and treatment decisions.
Related Tools
Endotracheal Tube Size Calculator
Paper Quantity Converter
Image Color Picker
Division Calculator
IP to Binary Converter
Visualize Time Intervals
Cash Out Refinance Calculator
Black Friday Calculator
Convert Roman Numeral to Hex
Cantor Set Generator
Terms and Condition Generator
Color Converter
ROAS Calculator
Credit Card Generator
Rabbit Gestation Calculator
Real Rate of Return Calculator
Inverse Function Calculator
Central Limit Theorem Calculator
Tap and Hold Image Maker
LED Savings Calculator