Cardiac output (CO) is the volume of blood pumped by the heart per minute, calculated as the product of heart rate (HR) and stroke volume (SV). It's the most fundamental measure of cardiac performance and is central to assessing heart failure, shock, and exercise capacity. Our cardiac output calculator computes CO in L/min and the cardiac index (CO ÷ body surface area) in L/min/m², the body-size-normalized version that's more useful for clinical comparisons.
Input resting or measured heart rate in bpm.
Provide stroke volume per beat in mL (typically 60-100).
Add body surface area for cardiac index.
Review cardiac output and category.
Cardiac output equals heart rate times stroke volume. A typical resting adult: 70 bpm × 70 mL = 4,900 mL/min ≈ 4.9 L/min. During peak exercise it can rise to 20-25 L/min in trained athletes. Cardiac index normalizes for body size — normal range 2.5-4.0 L/min/m².
CO = HR × SV / 1000 • CI = CO / BSA
Normal resting CO: 4-8 L/min for healthy adults
Cardiac index 2.5-4.0 L/min/m² is the body-size-normalized normal range
Peak exercise CO can reach 20-25 L/min in trained endurance athletes
Low CO with normal HR suggests low stroke volume — possible heart failure
High CO is normal during exercise, fever, hyperthyroidism, or pregnancy
CO can be measured directly via thermodilution (Swan-Ganz) or estimated via echocardiography
Cardiac output is one of the most critical hemodynamic parameters in clinical medicine, representing the total volume of blood the heart pumps per minute. Normal resting cardiac output ranges from 4 to 8 liters per minute in adults, calculated as the product of heart rate and stroke volume. Clinicians monitor cardiac output to assess heart failure severity, guide fluid resuscitation in sepsis, manage critically ill patients in the ICU, and evaluate the effectiveness of vasoactive medications. The cardiac index — cardiac output normalized to body surface area — provides a size-adjusted measure that allows meaningful comparisons between patients of different body sizes. A cardiac index below 2.2 L/min/m-squared typically indicates cardiogenic shock, while values above 4.0 may suggest a hyperdynamic state seen in early sepsis or thyrotoxicosis. This cardiac output calculator computes CO from heart rate and stroke volume, derives cardiac index using the Du Bois body surface area formula, calculates stroke volume index, and classifies the hemodynamic profile. It serves as a rapid bedside reference for nurses, medical students, and clinicians interpreting hemodynamic data.
Cardiac output is the most direct measure of how much blood the heart delivers to the body each minute. Every clinical assessment of heart failure, shock, and exercise capacity ultimately comes back to CO. It's also the framework for understanding why treatments work — increasing HR, increasing contractility, or reducing afterload all improve CO via different mechanisms.
Data sourced from trusted institutions
All formulas verified against official standards.