Cardiac Output Calculator
From each heartbeat to every minute. See the volume your heart pumps.
Your Measurements
Illustrative equipment — enter clinically measured values.
What the Numbers Mean
Heart rate · Beats per minute
How often your heart beats.
Stroke volume · Blood per beat
The volume pumped by one ventricle in one beat.
Use the Right Inputs
- Stroke volume requires a clinical measurement or estimate.
- A pulse oximeter does not measure stroke volume.
- Keep the activity level and timing consistent.
Your Cardiac Output
The Two Building Blocks
—Heart rate
—Entered stroke volume
Photos are illustrative; stroke volume is supplied by the user.
How Is This Calculated?
CO = HR × SV
A Closer Look at the Measurements
Record heart rate
Use beats per minute from the same period.
Obtain stroke volume
Use a clinically measured or estimated value.
Match the measurement conditions
Record the time, activity level and units.
Calculation & Assumptions
Formula: CO = HR × SV
Units: bpm × mL/beat = mL/min.
Conversion: Divide by 1,000 for L/min.
Input limits & precision
Heart rate must be greater than 0 and at most 500 bpm. Stroke volume must be greater than 0 and at most 1,000 mL/beat. Each input supports up to six decimal places. These are software limits, not clinical reference ranges. The calculation uses exact scaled-integer multiplication. The main L/min result is rounded to two decimals; tiny positive values are shown as < 0.005 L/min instead of zero. Worked formulas and exports retain the unrounded product.
Frequently asked questions
What is cardiac output?
Cardiac output is the volume of blood pumped by one ventricle in one minute. With heart rate in bpm and stroke volume in mL/beat, their product gives mL/min; divide by 1,000 to express it in L/min.
Where does stroke volume come from?
Stroke volume must come from a clinical measurement or estimate, for example an echocardiographic assessment. It cannot be obtained from the pulse reading alone.
Is cardiac output the same as cardiac index?
No. Cardiac index is cardiac output divided by body surface area. This calculator does not use body surface area and does not calculate cardiac index.
More questions (5)
What does the Cardiac Output calculate?
Cardiac Output Calculator Calculate cardiac output — the volume of blood your heart pumps each minute. Enter heart rate and stroke volume, and this calculator multiplies them (and converts to litres) to give cardiac output in L/min, with how it compares t — free online calculator.
Which values should I enter?
Enter Heart Rate, Stroke Volume using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: Cardiac Output = Heart Rate × Stroke Volume.
Why might my result differ from another source?
Results can differ because measurement methods, rounding and assumptions vary. This calculator is an estimate and is not a medical diagnosis.
Does the result update automatically?
Yes. Changing an input updates the result using the same calculation engine shown on this page.
Sources & References
Understanding cardiac outputCleveland Clinic · Health LibraryNCBIBookshelfPhysiology, Cardiac OutputNCBI Bookshelf · StatPearls
References provide context, not endorsement.