Cardiac Output Calculator
Calculate cardiac output (CO) from heart rate (HR) and stroke volume (SV). CO = HR x SV. Also compute cardiac index (CI) from body surface area. Essential for cardiovascular physiology.
❤️ Physiology📐 CO = HR x SV🧬 Biology
Heart rate HR (bpm)
Stroke volume SV (mL)
Body surface area BSA (m², optional)
Please enter valid values.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| Cardiac Output Calculator | — | CO = HR x SV | L/min |
Step-by-Step Examples
Example 1
Resting Adult
HR=70 bpm, SV=70mL.
- CO = 70 x 70 = 4900 mL/min = 4.9 L/min
- Normal resting CO: 4-6 L/min
- Pumps ~70 mL per beat
✓ CO = 4.9 L/min (normal resting)
Example 2
Cardiac Index
HR=75, SV=80mL, BSA=1.8m².
- CO = 75x80/1000 = 6.0 L/min
- CI = 6.0/1.8 = 3.33 L/min/m²
- Normal CI: 2.2-4.0 L/min/m²
✓ CO=6.0 L/min, CI=3.33
Example 3
Exercise
HR=150 bpm, SV=120mL (trained athlete).
- CO = 150x120/1000 = 18 L/min
- Elite athletes: CO up to 40 L/min at max
- SV increases with training (Frank-Starling law)
✓ CO=18 L/min at moderate exercise
Real-World Applications
Cardiology
CO monitoring guides treatment in heart failure and septic shock.
Exercise Physiology
CO determines O2 delivery to working muscles.
Intensive Care
CO measurement by Swan-Ganz or echocardiography guides hemodynamic management.
Clinical Research
CO response to interventions measured in cardiovascular trials.
Common Mistakes to Avoid
⚠️
Confusing CO with cardiac index
CO is absolute. CI = CO/BSA adjusts for body size. Always use CI to compare patients of different sizes.
⚠️
Assuming constant SV
SV changes with preload, afterload, and contractility. Heart rate alone doesn't determine CO.
⚠️
Not accounting for heart rate changes
At high HR, diastolic filling time decreases, reducing SV. CO may not increase proportionally with HR.
Frequently Asked Questions
What is normal cardiac output? ▾
4-8 L/min at rest in adults. ~5 L/min average. Increases 4-6x during maximal exercise in elite athletes.
What is stroke volume? ▾
Blood ejected per beat. Normal: 60-100 mL at rest. Determined by: preload (filling), afterload (resistance), contractility.
What is the Frank-Starling law? ▾
The greater the stretch of cardiac muscle (more preload/filling), the stronger the contraction and greater the SV. Explains why CO increases with exercise.
What is ejection fraction? ▾
EF = SV/End-diastolic volume x 100%. Normal: 55-70%. EF < 40%: heart failure. EF is a key clinical measure of systolic function.
What causes low cardiac output? ▾
Heart failure, cardiomyopathy, tamponade, severe arrhythmia, massive PE. Causes tissue hypoxia and shock if severe.