Cardiac Index Calculator

Calculate your Cardiac Index (CI) by entering cardiac output (or stroke volume and heart rate), along with height and weight. You'll get the CI in L/min/m², your estimated body surface area, and a classification of whether your cardiac function falls within the normal range of 2.6–4.2 L/min/m².

Disclaimer: This tool is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making any health-related decisions.

Input Method *

L/min

Volume of blood pumped by the left ventricle per minute

mL

Volume of blood ejected per heartbeat

bpm

Number of heartbeats per minute

cm
kg

Results

Cardiac Index (CI)

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Body Surface Area (BSA)

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Cardiac Output Used

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CI Classification

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Frequently Asked Questions

What is cardiac index?

Cardiac index (CI) is a hemodynamic parameter that assesses how well the heart is functioning as a pump by relating cardiac output to body surface area. It normalizes cardiac output for a patient's body size, making it a more accurate measure of cardiac performance than cardiac output alone. The unit is L/min/m².

What is the normal range for cardiac index?

The normal resting cardiac index is 2.6–4.2 L/min/m². Values below 2.6 L/min/m² may indicate reduced cardiac function, while values above 4.2 L/min/m² may suggest a hyperdynamic state. Always interpret results in clinical context with a healthcare professional.

What is the cardiac index formula?

Cardiac Index is calculated as CI = CO / BSA, where CO is cardiac output (L/min) and BSA is body surface area (m²). Alternatively, CI = (SV × HR) / BSA, where SV is stroke volume in liters and HR is heart rate in beats per minute. BSA is calculated using the Haycock formula: BSA = 0.024265 × height(cm)^0.3964 × weight(kg)^0.5378.

How is body surface area (BSA) calculated?

This calculator uses the Haycock formula: BSA (m²) = 0.024265 × height(cm)^0.3964 × weight(kg)^0.5378. This is one of the most widely validated BSA formulas used in clinical medicine. For an adult of average height (170 cm) and weight (70 kg), BSA is approximately 1.80 m².

What does a low cardiac index mean?

A cardiac index below 2.6 L/min/m² may indicate cardiogenic shock or reduced cardiac function. Severely low values (below 1.8 L/min/m²) are associated with cardiogenic shock. Clinical signs, other hemodynamic parameters, and patient history must all be considered when interpreting a low CI.

What is the difference between cardiac output and cardiac index?

Cardiac output (CO) is the total volume of blood the heart pumps per minute, typically 4–8 L/min in adults. Cardiac index (CI) adjusts this value for body surface area, allowing fair comparison between patients of different sizes. A large person naturally has a higher absolute CO, so CI provides a more meaningful assessment of heart function.

When is cardiac index used clinically?

Cardiac index is commonly used in intensive care units (ICU), cardiac ICUs, and during cardiac catheterization to evaluate heart function and guide treatment. It helps clinicians assess the severity of heart failure, monitor response to therapy, and identify cardiogenic shock.

Can I calculate cardiac index without knowing cardiac output directly?

Yes. If you don't have a direct cardiac output measurement, you can calculate it from stroke volume and heart rate: CO = (SV × HR) / 1000 (converting mL to L). This calculator supports both methods — simply select 'Stroke Volume & Heart Rate' as your input method.