bpm
Normal resting: 60–100 bpm
Enter heart ratemL
Normal: 60–100 mL per beat
Enter stroke volumecm
For cardiac index (BSA) calculation
Enter heightkg
For body surface area (BSA)
Enter weightCardiac Output (CO)
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⚠️ For educational and reference purposes only. This calculator is not a diagnostic tool. Clinical cardiac output measurement requires specialized equipment. Always consult a qualified healthcare professional for medical decisions.
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Understanding Cardiac Output
Cardiac output (CO) is the total volume of blood the heart pumps per minute. It is the product of heart rate and stroke volume, and represents the heart's ability to meet the body's circulatory demands. Normal resting CO is 4–8 L/min.
Cardiac Output Formula
CO (L/min) = Heart Rate (bpm) × Stroke Volume (mL) ÷ 1000
BSA (Mosteller formula) = √(Height(cm) × Weight(kg) / 3600)
Cardiac Index (CI) = CO ÷ BSA
Example: HR 72 bpm, SV 70 mL, BSA 1.8 m²:
CO = 72 × 70 ÷ 1000 = 5.04 L/min
CI = 5.04 ÷ 1.8 = 2.8 L/min/m²
Cardiac Index (CI) = CO ÷ BSA
Example: HR 72 bpm, SV 70 mL, BSA 1.8 m²:
CO = 72 × 70 ÷ 1000 = 5.04 L/min
CI = 5.04 ÷ 1.8 = 2.8 L/min/m²
Normal Reference Ranges
- Cardiac Output (CO): 4.0–8.0 L/min at rest
- Cardiac Index (CI): 2.5–4.0 L/min/m²
- Stroke Volume (SV): 60–100 mL per beat
- Heart Rate: 60–100 bpm (resting adult)
🫀 Clinical note: A cardiac index below 2.2 L/min/m² may indicate cardiogenic shock. Values above 4.0 L/min/m² can occur in high-output states such as sepsis, anemia, or hyperthyroidism. These are reference values — clinical diagnosis requires full hemodynamic assessment.
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Frequently Asked Questions
What is cardiac output?
Cardiac output (CO) is the volume of blood pumped by the heart per minute. It equals heart rate multiplied by stroke volume. Normal cardiac output at rest is 4–8 liters per minute and is a key indicator of heart function and circulatory efficiency.
What is the cardiac output formula?
CO = Heart Rate × Stroke Volume ÷ 1000. For example, HR 70 bpm × SV 70 mL ÷ 1000 = 4.9 L/min. Cardiac Index (CI) = CO ÷ Body Surface Area, normalizing output for body size to allow comparison between patients.
What is a normal cardiac output?
Normal cardiac output at rest is 4–8 L/min for adults. Cardiac index is normally 2.5–4.0 L/min/m². During exercise, CO can increase to 20–25 L/min in healthy individuals and up to 40 L/min in elite athletes.
What is stroke volume?
Stroke volume (SV) is the amount of blood ejected by the left ventricle with each heartbeat, typically 60–100 mL at rest. It is determined by preload (blood entering the heart), afterload (resistance against pumping), and myocardial contractility.
What is cardiac index?
Cardiac index (CI) is cardiac output divided by body surface area (BSA): CI = CO ÷ BSA. Normal CI is 2.5–4.0 L/min/m². A CI below 2.2 may indicate cardiogenic shock or severe heart failure and requires immediate clinical evaluation.