Cardiac Index Calculator

Written by Great Medico

Updated September 24, 2026 •2 min read

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When pressures, flows, or imaging measurements are involved, a clear equation matters. Cardiac Index Calculator shows how the values entered combine into the reported result.

What this calculator does

Cardiac index adjusts cardiac output for body surface area, making blood-flow output easier to compare across different body sizes. This calculator can start from a known cardiac output or calculate output from stroke volume and heart rate. Cardiovascular measurements are highly context-dependent, and technique, symptoms, medications, and the rest of the clinical assessment can be as important as the calculated value.

How to use it

Choose whether cardiac output is already known. If yes, enter cardiac output plus height and weight. If no, enter stroke volume and heart rate so the calculator can derive cardiac output, along with height and weight for body surface area.

How the calculation works

If cardiac output is entered, the tool uses it directly. Otherwise, cardiac output = stroke volume × heart rate ÷ 1,000. Body surface area is calculated with the Haycock equation from height and weight, and cardiac index = cardiac output ÷ body surface area.

Example

For the sample values prefilled in this calculator, the primary result is 2.609 L/min/m² (Normal cardiac index range), Cardiac output is 5 L/min, and BSA (Haycock) is 1.917 m². This example is there to show how the inputs flow through the implemented equation; replace the sample values with your own measurements before using the result.

How to interpret the result

The calculator labels values from 2.5 to 4.0 L/min/m² as its normal range, 2.0 to under 2.5 as below normal, below 2.0 as highly concerning in its stored interpretation, and above 4.0 as above normal. The number should be interpreted with perfusion, blood pressure, filling pressures, oxygenation, and the clinical situation.

Limitations and notes

Cardiac index alone cannot diagnose cardiogenic shock. Measurement method, rhythm, valve disease, preload, medications, sepsis, anemia, and body-surface-area estimation can all alter interpretation. A critically ill patient requires direct clinical and hemodynamic assessment.