ejection fraction calculation formula

What is ejection fraction?

Ejection fraction (EF) is the percentage of blood pumped out of the left ventricle with each heartbeat. It is one of the most commonly used measurements in cardiology because it provides a quick snapshot of left ventricular systolic function.

In simple terms, the ventricle fills with blood, then contracts. EF tells you what fraction of that filled volume is actually ejected forward during contraction.

The ejection fraction calculation formula

The standard ejection fraction calculation formula uses two measured volumes:

• EDV (End-Diastolic Volume): volume in the ventricle at the end of filling (diastole).
• ESV (End-Systolic Volume): volume remaining in the ventricle after contraction (systole).

Formula: EF = ((EDV − ESV) / EDV) × 100

You can also think of it as:

• Stroke Volume (SV) = EDV − ESV
• EF = (SV / EDV) × 100

Worked example

Suppose EDV is 130 mL and ESV is 55 mL.

• SV = 130 − 55 = 75 mL
• EF = (75 / 130) × 100 = 57.7%

That value usually falls in a broadly normal range for left ventricular ejection fraction.

How EF values are commonly interpreted

Ranges vary slightly among guidelines and clinical contexts, but a common practical framework is:

• < 40%: reduced ejection fraction
• 40–49%: mildly reduced / borderline zone
• 50–70%: often considered normal in many adults
• > 70%: hyperdynamic range; can be normal in some settings, but context matters

Where the numbers come from

1) Echocardiography (most common)

Echo estimates EDV and ESV using imaging planes and algorithms (such as Simpson’s biplane method). It is widely available and noninvasive, making it the most common source for EF.

2) Cardiac MRI

Cardiac MRI is often considered highly accurate for ventricular volume quantification, especially when echo windows are limited.

3) Nuclear imaging and CT

These modalities can also estimate EF in selected cases, often for specific clinical indications.

Common mistakes in EF calculation

• Mixing units (for example, mL with different scaling assumptions)
• Using inconsistent measurements from different beats or methods
• Entering ESV greater than EDV due to data-entry errors
• Treating EF as the only marker of heart function

Important limitations

EF is useful but incomplete. A person can have symptoms of heart failure even with a preserved EF. Conversely, a low EF does not describe the whole patient by itself. Clinical decisions also include symptoms, blood pressure, wall motion, valve disease, rhythm, biomarkers, and comorbid conditions.

Quick summary

• Use EDV and ESV to calculate EF.
• Apply: EF (%) = ((EDV − ESV) / EDV) × 100.
• Interpret EF in full clinical context, not in isolation.