What is a normal fractional shortening value?

In adults, FS% of 25–45% is considered normal. Values below 25% suggest reduced LV systolic function, while values above 45% may indicate a hyperdynamic state (e.g., volume overload, anemia) or hypertrophic cardiomyopathy.

What is the difference between FS% and ejection fraction (EF)?

EF measures the volumetric fraction of blood ejected per beat and requires 2D or 3D echo. FS% is a linear (one-dimensional) surrogate derived from M-mode diameters only. For a normally shaped (non-dilated) ventricle, EF ≈ 1.7 × FS% is sometimes used as a rough estimate, but EF is the preferred measure when available.

Can I use centimeters instead of millimeters?

The formula is unit-agnostic — as long as both LVEDD and LVESD are entered in the same unit, the FS% result is identical. This calculator uses mm, which is the most common unit in echo reports. Enter cm values only if you convert both inputs to the same unit before entering.

Why is LVESD sometimes larger than LVEDD in my inputs?

LVEDD is always the larger value because the ventricle is fully relaxed and filled at end-diastole. If you enter LVESD > LVEDD the calculator will flag an error. Recheck your echo measurements — a common mistake is swapping the diastolic and systolic calipers on the M-mode tracing.

Is fractional shortening valid in patients with wall motion abnormalities?

M-mode FS% assumes symmetric contraction. In patients with regional wall motion abnormalities (e.g., post-MI), FS% may be misleading because the M-mode cursor samples only one segment of the wall. Biplane Simpson ejection fraction is preferred in such cases.

Fractional Shortening Calculator

Name: Fractional Shortening Calculator
Availability: InStock
Author: Nham Vu

Enter LVEDD and LVESD from an echocardiogram to calculate fractional shortening (FS%) and see whether LV systolic function is normal, mildly reduced, or severely impaired.

Echo Measurements

Enter M-mode LV internal diameters in millimeters (mm).

LVEDD — LV end-diastolic diameter (mm)

Normal adult range: 42–58 mm (women), 42–60 mm (men)

LVESD — LV end-systolic diameter (mm)

Normal adult range: 26–40 mm (women), 26–40 mm (men)

Result

Enter LVEDD and LVESD to see the result.

FS% Interpretation Reference

FS% Range	Interpretation	Clinical note
< 18%	Severely reduced	Significant systolic dysfunction; typically EF < 30%
18–24%	Mildly to moderately reduced	LV systolic impairment; correlates with EF 30–45%
25–45%	Normal	Normal LV systolic function; EF typically 50–75%
> 45%	Hyperdynamic	Consider volume overload, anemia, hypertrophic states

Reference ranges are for adult patients. Pediatric norms differ; consult age-specific tables. FS% assumes symmetric LV contraction — not reliable with regional wall motion abnormalities.

Summary

Enter LVEDD and LVESD from an echocardiogram to calculate fractional shortening (FS%) and see whether LV systolic function is normal, mildly reduced, or severely impaired.

How it works

Measure LV internal diameter at end-diastole (LVEDD) from the M-mode echocardiogram tracing.
Measure LV internal diameter at end-systole (LVESD) from the same tracing.
Enter both values in millimeters (mm) into the calculator.
FS% is computed as (LVEDD − LVESD) / LVEDD × 100.
Compare the result against the normal reference range (25–45%) to interpret LV systolic function.

Use cases

Screen for LV systolic dysfunction in adult echocardiography reports.
Monitor LV function serially in patients on cardiotoxic chemotherapy.
Assess pediatric cardiac function — FS% is particularly common in pediatric echo.
Cross-check automated echo software measurements during manual review.
Estimate systolic function when ejection fraction (EF) is not directly reported.
Teach echo trainees the relationship between FS% and EF (EF ≈ 2 × FS for spherical ventricles).

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu