Cardiac Output Calculator

Calculate cardiac output based on stroke volume and heart rate to assess heart function and blood circulation efficiency.

How to Use This Calculator

Enter the stroke volume in milliliters (mL)
Enter the heart rate in beats per minute (bpm)
Optionally, enter the body surface area in square meters (m²)
Select your preferred unit system (metric or imperial)
Click Calculate to see the cardiac output and optionally the cardiac index

Formula Used

Cardiac Output = Stroke Volume × Heart Rate

Where:

Cardiac Output = Volume of blood pumped by the heart per minute
Stroke Volume = Volume of blood pumped by the heart in one beat
Heart Rate = Number of heart beats per minute

Cardiac Index = Cardiac Output ÷ Body Surface Area

Where:

Cardiac Index = Cardiac output normalized to body size
Body Surface Area = Total surface area of the body in square meters

Example Calculation

Real-World Scenario:

A 45-year-old patient is being evaluated for cardiovascular health. The echocardiogram shows a stroke volume of 70 mL and the patient's heart rate is 72 bpm.

Given:

Stroke Volume = 70 mL
Heart Rate = 72 bpm
Body Surface Area = 1.8 m²

Calculation:

Cardiac Output = 70 mL × 72 bpm = 5040 mL/min or 5.04 L/min

Cardiac Index = 5040 mL/min ÷ 1.8 m² = 2800 mL/min/m² or 2.8 L/min/m²

Result: The patient has a normal cardiac output of 5.04 L/min and a cardiac index of 2.8 L/min/m², which falls within the normal range of 2.5-4.2 L/min/m².

Why This Calculation Matters

Practical Applications

Assessing heart function in patients with cardiovascular disease
Evaluating the effectiveness of heart medications
Monitoring critically ill patients in intensive care
Determining fitness level and cardiovascular health

Key Benefits

Helps diagnose heart conditions and circulatory problems
Guides treatment decisions for cardiovascular patients
Provides a standardized measure of heart performance
Allows comparison between patients of different body sizes

Common Mistakes & Tips

Ensure all measurements use consistent units. Stroke volume should be in milliliters (mL) and heart rate in beats per minute (bpm). If you need to convert from other units, do so before entering the values to avoid calculation errors.

Cardiac output values vary significantly based on age, fitness level, body size, and health conditions. Always interpret results in the context of the individual patient's characteristics and clinical situation rather than relying solely on reference ranges.

Frequently Asked Questions

For a healthy adult at rest, the normal cardiac output is approximately 4-8 liters per minute. However, this can vary based on body size, age, and physical condition. During exercise, cardiac output can increase to 20-30 liters per minute in trained athletes.

In clinical settings, cardiac output is measured using various methods including thermodilution (using a pulmonary artery catheter), Doppler echocardiography, impedance cardiography, and the Fick principle. The method chosen depends on the clinical situation and available equipment.

Cardiac output is influenced by numerous factors including heart rate, stroke volume, preload (volume of blood in ventricles at end of diastole), afterload (pressure the heart must work against), contractility (intrinsic strength of cardiac muscle), autonomic nervous system activity, hormones, medications, body position, temperature, and emotional state.

References & Disclaimer

Medical Disclaimer

This calculator is for educational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

References

Physiology, Cardiac Output - StatPearls Publishing, 2023
Recommendations for Cardiac Chamber Quantification - American Heart Association, 2005
Cardiac Output Monitoring: A Review of Established and Novel Methods - Journal of Clinical Monitoring and Computing, 2016

Accuracy Notice

This calculator provides an estimate based on the values you input. Actual cardiac output measurements may vary based on the measurement technique and individual patient factors. The results should be interpreted by qualified healthcare professionals in the context of a complete clinical evaluation.

About the Author

Kumaravel Madhavan

Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.

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health medical-clinical-calculators cardiac output medical fitness body

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