Stroke Volume Calculator
Enter your measurements to calculate stroke volume, the amount of blood your heart ejects with each beat. Choose the method that matches your data: the volume method uses end-diastolic and end-systolic volumes, the hemodynamic method uses cardiac output and heart rate, and the Doppler method uses LVOT diameter and velocity-time integral from echocardiography. The calculator also returns ejection fraction, cardiac output, cardiac index, and stroke volume index.
What is stroke volume?
Stroke volume (SV) is the volume of blood the left ventricle ejects during a single heartbeat. It is determined by three fundamental factors: preload (how much blood fills the ventricle before contraction, reflected by end-diastolic volume), afterload (the resistance the ventricle must overcome to eject blood, largely driven by systemic vascular resistance), and contractility (the intrinsic force-generating capacity of the heart muscle independent of preload and afterload). A resting stroke volume of 60-100 mL is typical for healthy adults, and during vigorous exercise trained individuals can exceed 150-200 mL.
Three ways to calculate stroke volume
The volume method subtracts end-systolic volume from end-diastolic volume (SV = EDV - ESV), making it the most direct approach when ventricular volumes are available from cardiac imaging such as MRI or 3D echocardiography. The hemodynamic method rearranges the cardiac output equation (CO = HR x SV) to SV = CO / HR, useful when a pulmonary artery catheter or other continuous cardiac output monitor provides CO directly. The Doppler echo method uses the left ventricular outflow tract: SV = pi x (LVOT diameter / 2)^2 x LVOT VTI, where VTI (velocity-time integral) is the area under the pulsed-wave Doppler envelope, representing the distance blood travels per beat. All three methods produce values in millilitres per beat.
Ejection fraction, cardiac output, and indexed values
Ejection fraction (EF) is the proportion of EDV that is ejected as stroke volume: EF (%) = (SV / EDV) x 100. A normal EF is 55-75%. Values below 40% suggest reduced systolic function (heart failure with reduced ejection fraction, HFrEF), while values 40-54% are classified as mildly reduced (HFmrEF). Cardiac output (CO = SV x HR) is how much blood the heart pumps per minute. Body-size normalisation matters because a CO of 5 L/min is adequate for a 50 kg person but may be low for someone weighing 100 kg. Cardiac index (CI = CO / BSA) and stroke volume index (SVI = SV / BSA) account for body surface area using the Mosteller formula, allowing fair comparison across individuals and over time.
Clinical significance and factors affecting stroke volume
Stroke volume falls in conditions that reduce preload (dehydration, haemorrhage, venous pooling), increase afterload (hypertension, aortic stenosis), or impair contractility (myocardial infarction, cardiomyopathy). It rises with aerobic training (cardiac remodelling), sympathetic activation (exercise, catecholamines), and adequate volume loading. Monitoring trends in stroke volume and cardiac index is central to goal-directed haemodynamic therapy in critical care, where the aim is to optimise oxygen delivery to tissues. This calculator is an educational and screening tool - clinical management should always be guided by a qualified clinician using the full clinical picture.
Normal cardiovascular hemodynamic ranges (resting adult)
| Parameter | Normal range | Units |
|---|---|---|
| Stroke Volume (SV) | 60 - 100 | mL/beat |
| End-Diastolic Volume (EDV) | 100 - 160 | mL |
| End-Systolic Volume (ESV) | 40 - 70 | mL |
| Ejection Fraction (EF) | 55 - 75 | % |
| Cardiac Output (CO) | 4.0 - 8.0 | L/min |
| Cardiac Index (CI) | 2.5 - 4.0 | L/min/m² |
| Stroke Volume Index (SVI) | 33 - 47 | mL/beat/m² |
| Heart Rate (resting) | 60 - 100 | bpm |
| LVOT VTI (normal) | 18 - 25 | cm |
Values represent typical resting ranges for healthy adults. Athlete values may differ substantially.
Frequently asked questions
What is a normal stroke volume?
A resting stroke volume of 60-100 mL per beat is typical for healthy adults. Well-trained endurance athletes may have resting values of 100-120 mL, rising to 150-200 mL during maximal exercise, because regular aerobic training causes the heart to dilate and fill more efficiently (eccentric hypertrophy).
What is the difference between stroke volume and cardiac output?
Stroke volume is the blood ejected per beat, measured in mL/beat. Cardiac output is the total blood pumped per minute, equal to stroke volume multiplied by heart rate. A heart beating at 70 bpm with a stroke volume of 70 mL delivers a cardiac output of 4.9 L/min, which is roughly the entire blood volume circulating every minute at rest.
How does ejection fraction relate to stroke volume?
Ejection fraction is stroke volume expressed as a percentage of end-diastolic volume: EF = (SV / EDV) x 100. A normal EF of 55-75% means the heart ejects just over half to three-quarters of the blood that fills it with each beat. EF is a widely used marker of left ventricular systolic function in clinical cardiology.
What is the Doppler LVOT method and when is it used?
The Doppler method calculates stroke volume from pulsed-wave echocardiography at the left ventricular outflow tract (LVOT). The formula is SV = pi x (LVOT diameter / 2)^2 x LVOT VTI. It is commonly used in echocardiography labs, critical care, and for assessing aortic stenosis severity. It does not require ventricular volume measurements, making it practical when only Doppler data are available.
Why use cardiac index instead of cardiac output?
Cardiac output is not adjusted for body size, so a CO of 4 L/min may be adequate for a small adult but severely reduced for a large one. Cardiac index divides CO by body surface area (BSA), yielding a size-normalised value that allows meaningful comparison between individuals and across time in the same patient. Normal CI is 2.5-4.0 L/min/m².
Can I calculate stroke volume without imaging?
If you have cardiac output from a monitor and heart rate, you can use the hemodynamic method (SV = CO / HR) without any imaging. Cardiac output can be measured non-invasively using devices like bio-impedance monitors or finger photoplethysmography, as well as invasively via pulmonary artery catheters. The Doppler echo method requires echocardiography but still avoids direct volume measurements.