Ejection Fraction Calculator

1) What ejection fraction represents

Ejection fraction (EF) is a dimensionless efficiency ratio for a cyclic volume pump. It compares the ejected volume during one cycle to the maximum stored volume at peak fill. EF is unitless, so consistent unit conversion does not change it.

2) Core inputs and unit discipline

This calculator supports two data paths: EDV with ESV, or stroke volume with EDV. EDV is the maximum chamber volume, ESV is the minimum chamber volume, and SV is the difference. Keep all volumes in the same unit to avoid scale mistakes and rounding drift.

3) Computing SV, EF, and limits

The primary relationship is SV = EDV − ESV. EF then follows as EF = (SV/EDV) × 100%. Physical constraints enforce EDV > 0 and ESV < EDV for meaningful results.

4) Derived flow from heart rate

If heart rate (HR) is provided, the tool estimates flow as cardiac output CO = SV × HR. With SV in mL and HR in beats per minute, CO is reported in L/min after conversion by 1000 mL per liter. When body surface area is entered, cardiac index CI = CO/BSA is also computed.

5) Typical numeric ranges for verification

For quick checks, many textbook examples use EDV around 100–150 mL and ESV around 40–80 mL, giving SV near 60–80 mL. That produces EF values commonly between 50% and 70%. With HR near 60–80 bpm and SV near 70 mL, CO often lands near 4.2–5.6 L/min.

6) Measurement noise and uncertainty

Small errors in EDV and ESV can shift EF noticeably because EF depends on a ratio. The optional uncertainty panel applies first order propagation for EF = (1 − ESV/EDV)×100. Providing ± values lets the report show EF with an uncertainty band that is useful for sensitivity analysis.

7) Modeling and system interpretation

In a physics framing, EF acts like a volumetric efficiency for a compliant chamber with periodic boundary motion. It is useful when comparing pumping performance across different chamber sizes, materials, or drive frequencies. Because EF is normalized by EDV, it supports fair comparisons across scaled prototypes and simulations.

8) Reporting, reproducibility, and exports

Good reporting includes the chosen mode, unit, raw volumes, and the derived values SV and EF. When HR and BSA are used, include CO and CI so downstream calculations remain traceable. The CSV export supports spreadsheets, while the PDF export provides a compact single page record for lab notebooks.

1) Which inputs should I use?

Use EDV and ESV when you directly measured both volumes. Use SV and EDV when stroke volume is known from another method. The calculator will derive the missing quantity automatically.

2) Why must ESV be smaller than EDV?

EF assumes the chamber empties from EDV down to ESV during a cycle. If ESV is not smaller, the implied stroke volume becomes zero or negative, which is not physically meaningful in this model.

3) Do unit changes affect EF?

No. EF is a ratio of volumes, so it is invariant to consistent unit conversions. You can enter mL, L, or cm³ as long as EDV and ESV or SV use the same unit.

4) What does clamping EF to 0–100% mean?

Clamping prevents display of impossible percentages caused by typos or inconsistent inputs. The calculator still validates EDV and ESV relationships, but clamping provides an extra guardrail for noisy entries.

5) How is cardiac output computed here?

Cardiac output is computed as CO = SV × HR. SV is converted to liters per beat, then multiplied by beats per minute to return liters per minute. It is an estimate based on the provided inputs.

6) What do the uncertainty inputs represent?

They are plus or minus measurement uncertainties for EDV and ESV, in the same unit as your volumes. The calculator uses first order propagation to estimate how those uncertainties translate into an EF uncertainty.

7) Can I use this for non-biological pumps?

Yes. Any cyclic system with a maximum stored volume and a minimum residual volume can be described with an EF-like ratio. Interpret EDV as maximum volume, ESV as residual volume, and SV as delivered volume per cycle.