Spirometry values
Enter percent-predicted at minimum. Add z-scores and the LLN of the ratio for the most guideline-concordant output.
FEV₁/FVC ratio
FEV₁
FVC
Supporting (optional)
Post-bronchodilator (optional)
Suggested interpretation
Enter values and press Interpret.
Grading references
| Severity (z-score, 2022) | Severity (FEV₁ % pred) |
|---|---|
| Mild: −1.65 to −2.5 | Mild: ≥ 70% |
| Moderate: −2.5 to −4.0 | Moderate: 60–69% |
| Severe: < −4.0 | Mod-severe: 50–59% |
| Severe: 35–49% · Very severe: < 35% |
Obstruction: FEV₁/FVC below the LLN (z < −1.645). Bronchodilator responsiveness (2022): increase > 10% of the predicted value in FEV₁ or FVC.
Clinical decision support only. This is a suggested interpretation to speed reporting — it does not replace review of flow-volume loops, test quality/acceptability, prior studies, or the clinical context. Restriction cannot be diagnosed on spirometry alone and requires lung volumes (TLC). Verify before finalizing any report.
References: Stanojevic S, et al. ERS/ATS technical standard on interpretive strategies for routine lung function tests. Eur Respir J 2022;60:2101499. · Graham BL, et al. 2019 ATS/ERS standardisation of spirometry. · DLCO Hb correction: 2017 ERS/ATS DLCO standards (Cotes).