What this calculator does
The heart never empties completely. Ejection fraction measures what share of the blood in the left ventricle is actually pumped out with each beat, and a normal figure is only 50 to 70 per cent.
It is the central number in heart failure classification. An end-diastolic volume of 120 mL with 50 mL left behind gives 58.3 per cent, which is normal, while 70 mL left behind gives 41.7 per cent and falls into the mildly reduced category.
The formula
Stroke volume is end-diastolic volume less end-systolic volume. Ejection fraction is that stroke volume as a percentage of the end-diastolic volume.
| Term | Meaning |
|---|---|
| EDV | End-diastolic volume: blood in the ventricle just before it contracts. |
| ESV | End-systolic volume: blood remaining just after it contracts. |
| Stroke volume | The difference between the two, being what is actually ejected. |
The inputs explained
| Field | What to enter |
|---|---|
| End-diastolic volume (mL) | End-diastolic volume in mL, usually from echocardiography or cardiac MRI. |
| End-systolic volume (mL) | End-systolic volume in mL, from the same study. |
When to use it
Classifying heart failure
Treatment differs substantially between reduced and preserved ejection fraction.
Monitoring cardiac function
Some cancer treatments require ejection fraction monitoring for cardiotoxicity.
Understanding an echo report
The percentage follows directly from two measured volumes.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How does residual volume change the fraction?
The same filling volume with four end-systolic volumes.
| End-systolic volume | Ejection fraction | Stroke volume |
|---|---|---|
| 30 mL | 75.0% | 90 mL |
| 50 mL | 58.3% | 70 mL |
| 70 mL | 41.7% | 50 mL |
| 100 mL | 16.7% | 20 mL |
Questions
Why is 100 per cent not the goal?
Because the ventricle is never designed to empty. A residual volume is normal and provides reserve: during exercise the heart increases ejection fraction to raise output, which it could not do if it already emptied fully at rest.
What do HFrEF and HFpEF mean?
Heart failure with reduced and with preserved ejection fraction. Someone can have heart failure symptoms with a normal ejection fraction, because a stiff ventricle that fills poorly pumps out a normal fraction of a smaller volume.
How accurate is the measurement?
It varies more than the reported precision suggests. Echocardiographic estimates can differ by several points between operators and between methods, so a change of a few per cent between scans may not be real.
Can ejection fraction be too high?
Above about 70 per cent is unusual and can reflect hypertrophic cardiomyopathy or a hyperdynamic state, though it also frequently reflects a small ventricle or a measurement issue. It warrants interpretation rather than reassurance.
For total output per minute, see the cardiac output calculator. For cardiac workload, see the rate pressure product calculator.