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.
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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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.
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.
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.
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.
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.
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.
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.
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.