FEV1 to FVC Ratio Calculator

The FEV1 to FVC Ratio Calculator estimates your Tiffeneau-Pinelli index using FEV1, FVC, age, and gender. This tool helps patients and doctors assess lung function to screen for respiratory issues. Whether you are monitoring asthma, checking for COPD, or tracking treatment progress, this calculator provides quick, reliable insights into your pulmonary health.

Enter your FEV1 value in liters (L) or as a percentage of predicted value
Enter your FVC value in liters (L) or as a percentage of predicted value
Age is used for interpreting results based on normal ranges
Gender affects normal lung function values

How FEV1/FVC Ratio Is Calculated

The FEV1/FVC ratio measures the percentage of air you can forcefully exhale from your lungs in the first second compared to your total lung capacity. This calculation is the gold standard for identifying airflow obstruction and helps doctors distinguish between different types of lung disease.

FEV1/FVC Ratio = (FEV1 ÷ FVC) × 100%

Where:

  • FEV1 = Forced Expiratory Volume in 1 second
  • FVC = Forced Vital Capacity (total air exhaled)

To find this ratio, divide your FEV1 value by your FVC value. Multiplying by 100 converts the result into a percentage. This percentage is crucial because it remains relatively constant regardless of body size, making it a reliable indicator of airway health. Using age and gender helps ensure the results are compared to accurate normal ranges.

What Your FEV1/FVC Ratio Means

This number reveals how well air moves through your airways. A higher percentage generally means healthier lungs, while a lower percentage suggests blockage or narrowing.

Normal Lung Function (70% to 80% and above)

Your airways are open, and you exhale quickly. This range suggests healthy lungs or well-managed respiratory conditions.

Possible Obstruction (Below 70%)

Your airways may be narrowed or blocked. This pattern is common in conditions like asthma or COPD, making it hard to push air out fast enough.

Important: Normal values can drop slightly as you age, so older adults should interpret lower results carefully compared to younger individuals.

This tool provides estimates for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider to interpret your specific results and create a treatment plan.

Track your numbers over time to see if treatments are working or if your condition changes.