Cardiac index (CI) = cardiac output (CO) ÷ body surface area (BSA), in L/min/m². Enter a measured cardiac output plus weight and height; the tool computes BSA via the DuBois or Mosteller formula and interprets the result against the standard adult bands (normal 2.5–4.0).
| Cardiac index (L/min/m²) | Interpretation |
|---|---|
| ≤ 2.2 | Critically low — hemodynamic threshold for cardiogenic shock (SHARC) |
| 2.2 – 2.5 | Low — below the normal range |
| 2.5 – 4.0 | Normal (adult, resting) |
| > 4.0 | High — high-output state |
Example: CO 5.0 L/min, 70 kg, 175 cm → DuBois BSA ≈ 1.85 m² → CI ≈ 2.71 L/min/m² (normal).
Cardiac index (CI) is cardiac output (CO) divided by body surface area (BSA), expressed in L/min/m². Indexing to body size lets clinicians compare pump function fairly between a small and a large patient: the same cardiac output means something very different for each.
First find body surface area (BSA) from weight and height — either the DuBois formula (0.007184 × weight^0.425 × height^0.725, weight in kg and height in cm) or the simpler Mosteller formula (√(weight × height / 3600)). Then CI = cardiac output ÷ BSA. Example: CO 5.0 L/min with a DuBois BSA of 1.8481 m² gives 5.0 ÷ 1.8481 ≈ 2.71 L/min/m².
For adults at rest, the normal cardiac index is 2.5–4.0 L/min/m². Values of 2.2–2.5 are below normal. A CI of 2.2 or less is the accepted hemodynamic threshold used in the SHARC consensus definition of cardiogenic shock. Values above 4.0 are high.
Both are standard. DuBois (0.007184 × W^0.425 × H^0.725) is the classic formula used in cardiology references; Mosteller (√(WH/3600)) is simpler and agrees closely for typical adult body sizes. This calculator offers both so you can match the formula your institution or source uses.
Yes. Enter weight in kg or lb and height in cm or inches — the calculator converts internally (1 lb = 0.45359237 kg; 1 in = 2.54 cm) before applying the BSA formula.
A CI below 2.5 is below the normal range, and ≤ 2.2 is the hemodynamic threshold associated with cardiogenic shock in the SHARC consensus criteria. Low CI can occur in heart failure, severe hypovolemia, or obstructive shock — but a single number never makes a diagnosis; blood pressure, perfusion signs, and clinical context decide.
A CI above 4.0 L/min/m² is a high-output state, seen for example in sepsis, anemia, hyperthyroidism, or pregnancy. Like a low value, it is a prompt for clinical evaluation, not a diagnosis by itself.
This is a quick CI calculator: you supply an already-known cardiac output plus body size and get CI. The companion tool, Doppler Echo Cardiac Output, goes one step further back — it derives cardiac output itself from echocardiography measurements (LVOT diameter and velocity–time integral) and then reports CI as an option. Use the echo tool when you need to compute CO from Doppler data; use this one when CO is already measured (thermodilution, Fick, or echo).
No. This tool is for education only and must not drive clinical decisions. Cardiac output has to be measured by a clinician with appropriate equipment; interpret hemodynamic values together with a qualified professional.
Need to derive cardiac output from echo measurements first? See the companion Doppler Echo Cardiac Output calculator, which computes CO from LVOT diameter and VTI and reports cardiac index too.
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