Stroke Volume Calculator
Calculate stroke volume, cardiac output, ejection fraction, and cardiac index from echocardiographic measurements in seconds.
Enter LVEDD, LVESD, and heart rate to compute SV, EF, CO, and CI instantly.
Stroke Volume Calculator
Calculate stroke volume, cardiac output, ejection fraction, and cardiac index from echocardiographic measurements in seconds.
About the stroke volume calculator
Stroke volume (SV) is the amount of blood ejected by the left ventricle with each heartbeat. It is one of the most clinically important parameters in cardiology because it reflects the mechanical performance of the heart and determines how much blood reaches the systemic circulation per beat. Normal stroke volume in a resting adult typically ranges from 60 to 100 mL, depending on body size, fitness level, and cardiac health.
This calculator uses the simplified cube method (also known as the M-mode or Teichholz-derived approach) to estimate left ventricular volumes from standard echocardiographic diameter measurements. The end-diastolic volume (EDV) is computed as 0.523 × LVEDD³ and the end-systolic volume (ESV) as 0.523 × LVESD³, where the constant 0.523 approximates the volume of a prolate ellipsoid. Stroke volume is then EDV minus ESV.
Ejection fraction (EF) is expressed as (SV / EDV) × 100 and represents the percentage of blood in the left ventricle that is pumped out with each beat. Guidelines from the American Heart Association classify left ventricular EF as normal (≥55%), mildly reduced (45–54%), moderately reduced (30–44%), and severely reduced (<30%). EF is the cornerstone measure used to diagnose heart failure with reduced ejection fraction (HFrEF) versus heart failure with preserved ejection fraction (HFpEF).
Cardiac output (CO) is the total volume of blood the heart pumps per minute and equals SV multiplied by heart rate divided by 1000 (to convert mL/min to L/min). Normal CO at rest is 4–8 L/min. During exercise CO can rise to 20–25 L/min in healthy adults and even higher in trained athletes.
Cardiac index (CI) adjusts cardiac output for body size by dividing CO by body surface area (BSA) in m². This normalisation is useful when comparing patients of different body sizes or tracking a single patient over time as body weight changes. Normal CI is 2.5–4.0 L/min/m²; values below 2.2 L/min/m² suggest low cardiac output states such as cardiogenic shock.
Echocardiographic measurements should be obtained in the parasternal long-axis view at end-diastole (maximum LV dimension, onset of QRS on ECG) and end-systole (minimum LV dimension). Accurate measurement of LVEDD and LVESD requires a skilled sonographer and at least three cardiac cycles averaged to minimise beat-to-beat variability. This tool is designed for educational purposes and clinical estimation; it does not replace formal echocardiographic interpretation by a cardiologist.
Stroke volume calculator examples
Four clinical scenarios showing typical echocardiographic measurements and the derived cardiac parameters.
| Patient / Inputs | Key Results | Clinical Context |
|---|---|---|
| Healthy adult: LVEDD 5.0 cm, LVESD 3.2 cm, HR 70 bpm | SV ≈ 48 mL, EF ≈ 74%, CO ≈ 3.4 L/min | EDV ≈ 65 mL, ESV ≈ 17 mL — normal LV dimensions with preserved ejection fraction. |
| Heart failure: LVEDD 6.8 cm, LVESD 6.2 cm, HR 95 bpm | SV ≈ 40 mL, EF ≈ 24%, CO ≈ 3.8 L/min | EDV ≈ 165 mL, ESV ≈ 125 mL — severely dilated LV with severely reduced EF (<30%). |
| Trained athlete: LVEDD 5.5 cm, LVESD 3.3 cm, HR 52 bpm | SV ≈ 68 mL, EF ≈ 78%, CO ≈ 3.5 L/min | EDV ≈ 87 mL, ESV ≈ 19 mL — physiological LV enlargement with supranormal EF. |
| Elderly patient: LVEDD 4.8 cm, LVESD 3.1 cm, HR 78 bpm | SV ≈ 42 mL, EF ≈ 73%, CO ≈ 3.3 L/min | EDV ≈ 58 mL, ESV ≈ 16 mL — mildly reduced chamber size; preserved EF despite lower SV. |
How to use the stroke volume calculator
- Obtain LVEDD (Left Ventricular End-Diastolic Diameter) and LVESD (Left Ventricular End-Systolic Diameter) in centimetres from a standard M-mode or 2D echocardiogram in the parasternal long-axis view.
- Enter the patient's resting heart rate in beats per minute (bpm).
- Optionally enter the patient's body surface area (BSA) in m² to calculate cardiac index; leave it blank to skip CI.
- Click Calculate to display EDV, ESV, stroke volume, ejection fraction, cardiac output, and (if BSA is entered) cardiac index with reference ranges.
- Click Reset to clear all fields and start a new calculation.
Stroke volume calculator FAQ
What is a normal stroke volume?
A normal resting stroke volume in adults is approximately 60–100 mL per beat. Athletes often have higher values (90–110 mL) due to cardiac adaptations, while patients with heart failure may have significantly reduced stroke volumes despite an elevated heart rate.
What is the difference between cardiac output and cardiac index?
Cardiac output (CO) is the total volume of blood pumped per minute (L/min). Cardiac index (CI) normalises CO by body surface area (m²), allowing fair comparison between patients of different sizes. Normal CO is 4–8 L/min; normal CI is 2.5–4.0 L/min/m².
What is the cube method for calculating LV volumes?
The cube method estimates left ventricular volume as 0.523 × D³, where D is the linear diameter in cm. This approximates the LV as a prolate ellipsoid. It is simple and widely used in M-mode echocardiography, but may underestimate volumes in patients with asymmetric wall motion abnormalities.
What ejection fraction is considered reduced?
ACC/AHA guidelines define reduced EF (HFrEF) as EF less than 40%, mildly reduced EF as 40–49%, and preserved EF (HFpEF) as EF 50% or greater. The calculator uses ASE cut-offs: normal ≥55%, mildly reduced 45–54%, moderately reduced 30–44%, and severely reduced below 30%.
Can this calculator be used for right ventricular function?
No. The cube method applies to the left ventricle only. Right ventricular function is typically assessed with different parameters such as TAPSE (tricuspid annular plane systolic excursion), FAC (fractional area change), or right ventricular RVEF from 3D echo.
Why might my calculated EF differ from the echo report?
Echo reports usually use biplane Simpson's method of discs, which traces LV endocardial borders from two apical views. This is more accurate than the cube method, especially in patients with regional wall motion abnormalities. The cube method is a rapid bedside estimation and may differ by 5–10% from biplane measurements.