Predicted FEV1

The historical ERS/ECCS equations describe adults of European descent, aged 18–70, with height ranges 155–195 cm for males and 145–180 cm for females. For ages 18–25, an equation age of 25 is used (plateau convention). This tool does not apply an ethnicity multiplier and does not present this historical model as GLI Global or as a universal reference.

The ATS recommends a race-neutral approach using GLI Global rather than race/ethnicity-specific interpretation. For current clinical use, obtain the appropriate predicted value, LLN and z-score from a laboratory using the relevant reference equation. Laboratory mode here only uses the reference you enter; it does not reproduce the GLI engine.

The male and female coefficients belong to the historical equation. Patient characteristics and the reference model should be confirmed with the testing laboratory. Results outside the historical age or height range are not extrapolated; laboratory mode remains available.

Percent predicted = measured FEV1 ÷ unrounded reference ×100. Displayed liters have two decimals and percentage one decimal. The blue gauge is a linear 0–120% comparison; it is not a severity scale. Values above 120% keep their numeric percentage and cap only the marker. No measured value means no comparison marker or percentage.

Neither a fixed 80% cut-off nor FEV1 alone establishes normality or disease severity. Airflow obstruction requires the appropriate FEV1/FVC assessment, and restriction requires lung-volume confirmation. Spirometry quality, test conditions, symptoms and other clinical information matter. No LLN, z-score, disease diagnosis or treatment decision is generated here.

Laboratory reference entry 0.01–20 L and measured entry 0–20 L are numeric input safeguards, not clinical normal ranges. A zero measurement is displayed numerically without a severity diagnosis. The pictures are illustrations, not patient records or measuring devices.