Ankle-Brachial Index (ABI) Calculator
Ankle-Brachial Index (ABI) Calculator is a health and wellness calculator that helps you calculate ankle-brachial index (abi) values from your input data. The formula used is: ABI = Highest ankle systolic pressure ÷ Highest arm systolic pressure. Enter values using the units shown next to each input field (e.g. kg, cm, years).
Rates and fees change frequently. Always confirm the current figures
with the official authority before relying on this result.
- Screening calculation only. Diagnosis requires proper measurement and clinical assessment.
Formula
ABI = Highest ankle systolic pressure ÷ Highest arm systolic pressure
- Ankle-Brachial Index (ABI) Calculator gives you a fast estimate using your inputs and updates instantly when you change any value.
- Formula: ABI = Highest ankle systolic pressure ÷ Highest arm systolic pressure
- Input definitions: • Highest ankle systolic pressure: the higher of the dorsalis pedis and posterior tibial readings for that leg • Highest arm (brachial) systolic pressure: the higher of the two arm readings
- Manual method: write down each input, apply the formula step by step, then compare your manual result with the calculator output.
- Enter values using the units shown next to each input field (e.g. kg, cm, years).
- This calculator uses widely accepted health formulas and returns screening estimates only. It does not replace a diagnosis from a qualified healthcare professional.
- Compare your result with published reference ranges. Values outside the normal range warrant a conversation with your doctor.
- Practical tip: test a low, medium, and high scenario to understand sensitivity before making decisions.
Example Calculation
Inputs
- Highest ankle systolic pressure: 120 mmHg
- Highest arm (brachial) systolic pressure: 120 mmHg
With an ankle pressure of 120 mmHg and an arm pressure of 120 mmHg, ABI = 120 ÷ 120 = 1.0 — a normal result. A lower ankle pressure (say 90) would give 0.75, suggesting peripheral artery disease.
Frequently asked questions
What is the ankle-brachial index?
The ABI compares blood pressure at the ankle with that in the arm to screen for peripheral artery disease: ABI = highest ankle systolic ÷ highest arm systolic.
What ABI is normal?
About 1.0–1.4 is normal. 0.91–0.99 is borderline, 0.41–0.90 indicates mild-to-moderate disease, and ≤0.40 indicates severe disease. Above 1.4 suggests non-compressible, calcified arteries.
What units should I enter?
Enter both pressures in mmHg, using the higher reading at each site.
How accurate are the results?
The ratio is exact, but it is a screening tool. Accurate measurement with a Doppler and clinical assessment are needed for diagnosis.
How do I interpret a low ABI?
A reduced ABI suggests narrowed leg arteries and warrants follow-up with a clinician.
How can I verify the calculation manually?
Use the displayed formula and work through the numbers step by step. If your manual result differs slightly, check rounding and unit conversions first.
Can I use this for planning and budgeting?
Yes. Run best-case, expected, and worst-case inputs to compare outcomes and make safer planning decisions.
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