Cardiac Output Calculator
Use this cardiac output calculator to find your cardiac output and cardiac index from heart rate and stroke volume.
Updated September 18, 2026
Calculated instantly in your browser — nothing is sent to or stored on our servers.
Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How Cardiac Output Is Calculated
Cardiac output is the volume of blood the heart pumps per minute, and it comes down to just two things: how fast the heart is beating, and how much blood it ejects with each beat. Multiplying those together gives the full picture that either number alone can't¹.
What This Calculator Measures
This calculates cardiac output from heart rate and stroke volume, and cardiac index (output adjusted for body size) if height and weight are also provided. It's a physiology teaching tool, not a substitute for actual clinical cardiac assessment.
The Formula
Cardiac Output (L/min) = Heart Rate × Stroke Volume ÷ 1000
Cardiac Index (L/min/m²) = Cardiac Output ÷ Body Surface Area, calculated when height and weight are provided, using the Mosteller formula for BSA, the same method used on the Body Surface Area Calculator².
How This Calculator Computes Your Result
Enter heart rate and stroke volume. If you also enter height and weight, we calculate body surface area using the Mosteller formula and divide cardiac output by it to give cardiac index, which adjusts for body size and is more comparable across people of different sizes than raw cardiac output alone.
Why Cardiac Index Matters More Than Raw Cardiac Output for Comparison
Two people can have identical cardiac output but very different cardiac demands simply because they're different sizes, a larger body has more tissue to perfuse. Cardiac index accounts for this by dividing output by body surface area, which is why clinical reference ranges for adequate perfusion are typically expressed as cardiac index rather than raw cardiac output. It's the reason this calculator surfaces cardiac index as a second, more comparable number rather than stopping at the raw output figure.
A Note on Accuracy
This calculator is educational. Real clinical cardiac output assessment requires actual measurement (echocardiography, thermodilution, or other validated methods), not just multiplying two numbers a person estimates or recalls, and is interpreted by a clinician in the context of a full cardiovascular evaluation.
Frequently Asked Questions
Where does stroke volume come from?
Stroke volume normally comes from an echocardiogram or other clinical measurement, it's not something most people know off-hand or should estimate for this calculator.
What is cardiac index and why does it need height and weight?
Cardiac index adjusts cardiac output for body size by dividing it by body surface area (BSA), making it more comparable across people of different sizes. BSA is calculated from height and weight using the Mosteller formula, the same method used when calculating body surface area².
What are normal resting values?
Normal resting cardiac output is 4 to 8 L/min (average around 5 L/min); normal cardiac index is 2.5 to 4.0 L/min/m²¹. Both rise substantially with exercise and vary with age, sex, and body size.
Can I use this to check my heart health?
No. This is an educational physiology tool, not clinical decision support. Real cardiac output assessment requires actual clinical measurement interpreted by a clinician as part of a full cardiovascular evaluation.
Sources
Physiology, Cardiac Index, StatPearls, National Library of Medicine
Simplified Calculation of Body-Surface Area, Mosteller, R.D., New England Journal of Medicine, 1987
Cardiac Output Calculator
Use this cardiac output calculator to find your cardiac output and cardiac index from heart rate and stroke volume.
Updated September 18, 2026
Calculated instantly in your browser — nothing is sent to or stored on our servers.
Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How Cardiac Output Is Calculated
Cardiac output is the volume of blood the heart pumps per minute, and it comes down to just two things: how fast the heart is beating, and how much blood it ejects with each beat. Multiplying those together gives the full picture that either number alone can't¹.
What This Calculator Measures
This calculates cardiac output from heart rate and stroke volume, and cardiac index (output adjusted for body size) if height and weight are also provided. It's a physiology teaching tool, not a substitute for actual clinical cardiac assessment.
The Formula
Cardiac Output (L/min) = Heart Rate × Stroke Volume ÷ 1000
Cardiac Index (L/min/m²) = Cardiac Output ÷ Body Surface Area, calculated when height and weight are provided, using the Mosteller formula for BSA, the same method used on the Body Surface Area Calculator².
How This Calculator Computes Your Result
Enter heart rate and stroke volume. If you also enter height and weight, we calculate body surface area using the Mosteller formula and divide cardiac output by it to give cardiac index, which adjusts for body size and is more comparable across people of different sizes than raw cardiac output alone.
Why Cardiac Index Matters More Than Raw Cardiac Output for Comparison
Two people can have identical cardiac output but very different cardiac demands simply because they're different sizes, a larger body has more tissue to perfuse. Cardiac index accounts for this by dividing output by body surface area, which is why clinical reference ranges for adequate perfusion are typically expressed as cardiac index rather than raw cardiac output. It's the reason this calculator surfaces cardiac index as a second, more comparable number rather than stopping at the raw output figure.
A Note on Accuracy
This calculator is educational. Real clinical cardiac output assessment requires actual measurement (echocardiography, thermodilution, or other validated methods), not just multiplying two numbers a person estimates or recalls, and is interpreted by a clinician in the context of a full cardiovascular evaluation.
Frequently Asked Questions
Where does stroke volume come from?
Stroke volume normally comes from an echocardiogram or other clinical measurement, it's not something most people know off-hand or should estimate for this calculator.
What is cardiac index and why does it need height and weight?
Cardiac index adjusts cardiac output for body size by dividing it by body surface area (BSA), making it more comparable across people of different sizes. BSA is calculated from height and weight using the Mosteller formula, the same method used when calculating body surface area².
What are normal resting values?
Normal resting cardiac output is 4 to 8 L/min (average around 5 L/min); normal cardiac index is 2.5 to 4.0 L/min/m²¹. Both rise substantially with exercise and vary with age, sex, and body size.
Can I use this to check my heart health?
No. This is an educational physiology tool, not clinical decision support. Real cardiac output assessment requires actual clinical measurement interpreted by a clinician as part of a full cardiovascular evaluation.
Sources
Physiology, Cardiac Index, StatPearls, National Library of Medicine
Simplified Calculation of Body-Surface Area, Mosteller, R.D., New England Journal of Medicine, 1987
Cardiac Output Calculator
Use this cardiac output calculator to find your cardiac output and cardiac index from heart rate and stroke volume.
Updated September 18, 2026
Calculated instantly in your browser — nothing is sent to or stored on our servers.
Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How Cardiac Output Is Calculated
Cardiac output is the volume of blood the heart pumps per minute, and it comes down to just two things: how fast the heart is beating, and how much blood it ejects with each beat. Multiplying those together gives the full picture that either number alone can't¹.
What This Calculator Measures
This calculates cardiac output from heart rate and stroke volume, and cardiac index (output adjusted for body size) if height and weight are also provided. It's a physiology teaching tool, not a substitute for actual clinical cardiac assessment.
The Formula
Cardiac Output (L/min) = Heart Rate × Stroke Volume ÷ 1000
Cardiac Index (L/min/m²) = Cardiac Output ÷ Body Surface Area, calculated when height and weight are provided, using the Mosteller formula for BSA, the same method used on the Body Surface Area Calculator².
How This Calculator Computes Your Result
Enter heart rate and stroke volume. If you also enter height and weight, we calculate body surface area using the Mosteller formula and divide cardiac output by it to give cardiac index, which adjusts for body size and is more comparable across people of different sizes than raw cardiac output alone.
Why Cardiac Index Matters More Than Raw Cardiac Output for Comparison
Two people can have identical cardiac output but very different cardiac demands simply because they're different sizes, a larger body has more tissue to perfuse. Cardiac index accounts for this by dividing output by body surface area, which is why clinical reference ranges for adequate perfusion are typically expressed as cardiac index rather than raw cardiac output. It's the reason this calculator surfaces cardiac index as a second, more comparable number rather than stopping at the raw output figure.
A Note on Accuracy
This calculator is educational. Real clinical cardiac output assessment requires actual measurement (echocardiography, thermodilution, or other validated methods), not just multiplying two numbers a person estimates or recalls, and is interpreted by a clinician in the context of a full cardiovascular evaluation.
Frequently Asked Questions
Where does stroke volume come from?
Stroke volume normally comes from an echocardiogram or other clinical measurement, it's not something most people know off-hand or should estimate for this calculator.
What is cardiac index and why does it need height and weight?
Cardiac index adjusts cardiac output for body size by dividing it by body surface area (BSA), making it more comparable across people of different sizes. BSA is calculated from height and weight using the Mosteller formula, the same method used when calculating body surface area².
What are normal resting values?
Normal resting cardiac output is 4 to 8 L/min (average around 5 L/min); normal cardiac index is 2.5 to 4.0 L/min/m²¹. Both rise substantially with exercise and vary with age, sex, and body size.
Can I use this to check my heart health?
No. This is an educational physiology tool, not clinical decision support. Real cardiac output assessment requires actual clinical measurement interpreted by a clinician as part of a full cardiovascular evaluation.
Sources
Physiology, Cardiac Index, StatPearls, National Library of Medicine
Simplified Calculation of Body-Surface Area, Mosteller, R.D., New England Journal of Medicine, 1987