Cardiac Index Calculator

Calculate cardiac index (CI) by dividing cardiac output by body surface area. Enter a known BSA or estimate it from height and weight.

Calculator inputs

Body surface area (BSA)

Cardiac index result

Enter cardiac output and body surface area, or estimate BSA from height and weight.

Cardiac index = cardiac output ÷ BSA

How to calculate cardiac index

CI (L/min/m²) = CO (L/min) ÷ BSA (m²)

Use cardiac output (CO) in liters per minute and body surface area (BSA) in square meters. If the reported output is in mL/min, divide it by 1,000 before entering it.

Example with a known BSA

With a cardiac output of 5.4 L/min and a BSA of 1.80 m², divide 5.4 by 1.80 to get 3.00 L/min/m².

Example from height and weight

At 170 cm and 70 kg, the Du Bois BSA is about 1.81 m². With the same cardiac output of 5.4 L/min, the cardiac index is 2.98 L/min/m².

The Du Bois equation estimates BSA as 0.007184 × height (cm)0.725 × weight (kg)0.425. The calculator uses the full estimate and rounds the displayed values.

Cardiac index vs. cardiac output

Cardiac output is the volume of blood the heart pumps per minute. Cardiac index expresses that flow per square meter of body surface area, so the same cardiac output gives a lower index at a larger BSA.

What is the adult cardiac index reference range?

A typical adult reference range in invasive hemodynamic assessment is 2.5–4.0 L/min/m². Interpret the value with the method used to obtain cardiac output and the patient’s clinical context. AATS hemodynamic management primer

Related hemodynamics tools

Clinical references