Cardiac Output Calculator
Calculate cardiac output (CO), stroke volume (SV), heart rate (HR), cardiac index (CI), and ejection fraction (EF) with steps.
Background
Cardiac output helps students connect heart rate, stroke volume, and ventricular pumping performance to hemodynamics, perfusion, and cardiovascular function. This calculator combines core classroom formulas with guided interpretation, quick picks, and advanced measures such as cardiac index and ejection fraction.
How to use this calculator
- Choose Find Cardiac Output, Find Stroke Volume, Find Heart Rate, or Advanced Cardiac Measures.
- Enter the known values such as heart rate, stroke volume, end-diastolic volume, end-systolic volume, or body surface area. In Advanced mode, you can also turn on the BSA helper to estimate body surface area from height and weight.
- Click Calculate to see the result, formula, interpretation, and steps.
- Use the quick picks for common physiology-style examples.
How this calculator works
- Find Cardiac Output: uses heart rate and stroke volume with CO = HR × SV.
- Find Stroke Volume: uses ventricular filling and residual volume with SV = EDV − ESV.
- Find Heart Rate: rearranges the cardiac output formula to HR = CO / SV.
- Advanced Cardiac Measures: can calculate cardiac index, ejection fraction, stroke volume, and cardiac output from combined inputs.
- BSA helper: when enabled in Advanced mode, the calculator can estimate body surface area with the Mosteller equation instead of requiring direct BSA entry.
- Interpretation tools: the calculator can also show lower / typical / higher cardiac output ranges and a brief physiology note.
Formula & Equations Used
Cardiac Output: CO = HR × SV
Stroke Volume: SV = EDV − ESV
Heart Rate: HR = CO / SV
Cardiac Index: CI = CO / BSA
Ejection Fraction: EF = (SV / EDV) × 100
Mosteller BSA estimate: BSA = √((height in cm × weight in kg) / 3600)
Example Problems & Step-by-Step Solutions
Example 1 — Find Cardiac Output
Find the cardiac output if heart rate is 70 bpm and stroke volume is 70 mL/beat.
- Use CO = HR × SV.
- Substitute: CO = 70 × 70.
- Compute: CO = 4900 mL/min.
- Convert: 4900 mL/min = 4.9 L/min.
Example 2 — Find Stroke Volume
Find stroke volume if EDV = 120 mL and ESV = 50 mL.
- Use SV = EDV − ESV.
- Substitute: SV = 120 − 50.
- Compute: SV = 70 mL/beat.
Example 3 — Find Heart Rate
Find heart rate if CO = 5.6 L/min and SV = 70 mL/beat.
- Convert cardiac output: 5.6 L/min = 5600 mL/min.
- Use HR = CO / SV.
- Substitute: HR = 5600 / 70.
- Compute: HR = 80 bpm.
Example 4 — Advanced Measures
If HR = 72 bpm, EDV = 120 mL, ESV = 50 mL, and BSA = 1.9 m², find SV, CO, EF, and CI.
- SV = EDV − ESV = 120 − 50 = 70 mL/beat.
- CO = HR × SV = 72 × 70 = 5040 mL/min = 5.04 L/min.
- EF = (SV / EDV) × 100 = (70 / 120) × 100 = 58.3%.
- CI = CO / BSA = 5.04 / 1.9 = 2.65 L/min/m².
Frequently Asked Questions
Q: What is cardiac output?
Cardiac output is the amount of blood the heart pumps each minute. It depends on heart rate and stroke volume.
Q: What is stroke volume?
Stroke volume is the amount of blood ejected by the ventricle in one beat. It is commonly calculated as EDV − ESV.
Q: What is cardiac index?
Cardiac index adjusts cardiac output for body size using body surface area. It helps compare output across people of different sizes.
Q: What is ejection fraction?
Ejection fraction is the percentage of end-diastolic volume pumped out during contraction. It is calculated as (SV / EDV) × 100.
Q: Does a higher cardiac output always mean a healthier heart?
No. Cardiac output depends on the situation. Exercise can raise cardiac output normally, while some abnormal states can also raise or lower it.
Q: Does this calculator provide medical advice?
No. This calculator is designed for educational use and study support. Its interpretations should not replace professional medical evaluation.
Q: Can this calculator estimate body surface area (BSA)?
Yes. In Advanced mode, you can turn on the BSA helper and estimate body surface area from height and weight using the Mosteller equation.
