Stroke Volume
Calculate stroke volume (SV) from cardiac output and heart rate with our free online calculator. Get stroke volume index (SVI), clinical interpretation, and normal range comparison with charts.
Optional — Body Surface Area for Index
About This Calculator
The Stroke Volume Calculator helps you determine the amount of blood pumped by your heart in a single beat. Stroke volume (SV) is a key measure of cardiac function used by healthcare professionals in cardiology, anesthesiology, and critical care to assess how effectively the heart is pumping blood to the body.
Stroke volume is calculated using the formula SV = (Cardiac Output × 1000) / Heart Rate. For example, a person with a cardiac output of 5 L/min and a heart rate of 70 bpm has a stroke volume of approximately 71.4 mL. Normal resting stroke volume ranges from 60 to 120 mL per beat, though this can vary based on age, fitness level, and body size. Athletes often have higher stroke volumes, sometimes exceeding 200 mL, due to more efficient cardiac function from regular cardiovascular training.
Three primary factors influence stroke volume: preload (the amount of blood returning to the heart and filling the ventricles), contractility (the force of the heart muscle contraction), and afterload (the resistance the heart must overcome to eject blood). Changes in any of these factors — from conditions like heart failure, valvular disease, dehydration, or hyperthyroidism — can alter stroke volume. This is why stroke volume is a critical measurement in managing patients with cardiovascular disease, monitoring fluid status in critical care, and evaluating recovery after anesthesia.
This calculator also computes the stroke volume index (SVI) when height and weight are provided. SVI normalizes stroke volume to body surface area (BSA) using the Mosteller formula: √(height × weight / 3600). Normal SVI ranges from 33 to 47 mL/m². Indexing to BSA allows clinicians to compare cardiac function across patients of different body sizes — particularly important in pediatrics, obesity, and cachexia where uncorrected SV would be misleading.
Regional Notes
India (IN): Stroke volume assessment is widely used in Indian cardiology and critical care settings, particularly for patients with hypertensive heart disease, rheumatic heart disease, and ischemic cardiomyopathy. Echocardiography is the primary method for SV measurement in Indian hospitals.
United States (US): The American College of Cardiology and American Heart Association guidelines reference stroke volume and cardiac output in the management of heart failure, shock, and perioperative care. SVI is commonly used in advanced hemodynamic monitoring with pulmonary artery catheters and non-invasive cardiac output monitors.
United Kingdom (UK): The National Institute for Health and Care Excellence (NICE) guidelines incorporate stroke volume measurement in the assessment of heart failure, sepsis management, and intraoperative goal-directed fluid therapy. UK clinicians use Doppler echocardiography and LiDCO/PiCCO monitoring for SV determination in critical care.
Frequently Asked Questions
What is stroke volume and how is it calculated?
Stroke volume (SV) is the amount of blood pumped by the left ventricle in each heartbeat. It is calculated using the formula SV = Cardiac Output × 1000 / Heart Rate. For example, if cardiac output is 5 L/min and heart rate is 70 bpm, stroke volume = 5000 / 70 = 71.4 mL. Normal stroke volume ranges from 60 to 120 mL per beat.
What is a normal stroke volume range?
A normal stroke volume ranges from 60 to 120 mL per beat at rest. Trained athletes may have higher stroke volumes reaching 200 mL due to more efficient cardiac function. Values below 60 mL may indicate reduced cardiac function, while values above 120 mL may suggest a high-output state. Interpretation always requires clinical context by a healthcare professional.
What is stroke volume index and why is it important?
Stroke volume index (SVI) normalizes stroke volume to body surface area (BSA), calculated as SVI = SV / BSA. BSA is computed using the Mosteller formula: √(height × weight / 3600). This allows comparison of cardiac function across individuals of different body sizes. Normal SVI ranges from 33 to 47 mL/m². Healthcare providers use SVI to assess cardiac performance in patients of varying body types.
What factors affect stroke volume?
Stroke volume is influenced by three main factors: preload (ventricular filling volume, affected by blood volume and venous return), contractility (the heart muscle's pumping strength, affected by catecholamines, calcium levels, and medications), and afterload (the resistance the heart must overcome, affected by blood pressure and aortic valve function). Exercise, dehydration, heart failure, valvular disease, and certain medications can all alter stroke volume.
How is cardiac output related to stroke volume?
Cardiac output (CO) is the total volume of blood the heart pumps per minute and equals stroke volume multiplied by heart rate (CO = SV × HR). For a typical adult, cardiac output is 4–8 L/min. If stroke volume decreases, the heart may compensate by increasing heart rate to maintain cardiac output. Measuring both values provides a comprehensive picture of cardiovascular function.
How do IN, US, and UK measurement units differ for stroke volume?
Stroke volume is universally measured in milliliters (mL) in clinical settings worldwide including India, the United States, and the United Kingdom. Cardiac output is measured in liters per minute (L/min) globally. Heart rate is measured in beats per minute (bpm). Height is measured in centimeters (cm) and weight in kilograms (kg) for BSA calculation, though US clinicians may also use inches and pounds.
Can I use this calculator for medical diagnosis?
No. This stroke volume calculator is for educational and reference purposes only. It uses standard cardiovascular formulas but is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for interpretation of cardiac function values and any health concerns.