FEV1/FVC Ratio Calculator
Enter FEV1 and FVC values from the same spirometry test to calculate their ratio. The ratio alone does not grade COPD severity or diagnose asthma.
Use the FEV1/FVC Ratio Calculator
Spirometry Values
Typical range: 0.5 – 6.0 L
Typical range: 1.0 – 8.0 L
Interpretation Reference (Fixed 0.70 Ratio)
Obstruction severity (GOLD stages 1–4) requires FEV1 % predicted, not the ratio magnitude.
Enter FEV1 and FVC values, then click Calculate.
Your Result
Input Summary
Summary
The FEV1/FVC ratio compares forced expiratory volume in one second (FEV1) with forced vital capacity (FVC). GOLD uses a post-bronchodilator ratio below 0.70 as one component in confirming persistent airflow obstruction, while age-adjusted lower limits of normal may also be considered. Ratio magnitude alone does not assign a GOLD grade; grading requires FEV1 percent predicted, and diagnosis requires clinical context.
How it works
- Enter your FEV1 value in liters from your spirometry report.
- Enter your FVC value in liters from the same test.
- The calculator divides FEV1 by FVC and multiplies by 100 to get a percentage.
- The result is compared with the fixed 0.70 reference used by this educational tool.
- A result card explains the limitation of interpreting the ratio without reference values and clinical context.
Use cases
- Screen spirometry results for obstructive lung patterns.
- Check the arithmetic on a reported FEV1/FVC value.
- Compare paired pre- and post-bronchodilator ratios for discussion with a clinician.
- Learn how a ratio contributes to spirometry interpretation.
- Educate patients on their spirometry report findings.
- Prepare questions for a respiratory clinician.