The FEV1/FVC Ratio Calculator is a health tool that shows how well your lungs work. It calculates the percentage of your lung’s forced vital capacity (FVC) you can exhale in the first second of a forceful breath out (FEV1). Doctors and respiratory therapists use this value to help diagnose conditions like asthma, COPD, or other breathing problems.
formula of Fev1/Fvc Ratio Calculator
Basic Formula:
FEV1/FVC Ratio (%) = (FEV1 / FVC) × 100
Where:
- FEV1 (Forced Expiratory Volume in 1 Second): How much air you blow out in the first second, measured in liters or milliliters.
- FVC (Forced Vital Capacity): Total amount of air you can blow out forcefully after a deep breath, in the same unit.
- The result is a percentage (%) showing lung efficiency.
Tip:
Always use the same units (liters or milliliters) for FEV1 and FVC.
General Reference Table
| Term | What It Means | Typical Example |
|---|---|---|
| FEV1 | Air blown out in 1 second | 3.0 liters |
| FVC | Total air blown out | 4.0 liters |
| Normal Ratio | Healthy adults | 75%–80% |
Example of Fev1/Fvc Ratio Calculator
Sample Calculation:
- FEV1: 2.8 liters
- FVC: 3.5 liters
Step 1: Divide FEV1 by FVC
2.8 ÷ 3.5 = 0.8
Step 2: Convert to percentage
0.8 × 100 = 80%
FEV1/FVC Ratio = 80%
This shows healthy lung function for most adults.
Most Common FAQs
A: For healthy adults, it’s usually between 75% and 80%. Children may have slightly higher values.
A: A lower-than-normal ratio often suggests airway blockage, which can happen in diseases like asthma or chronic obstructive pulmonary disease (COPD).
A: No. Always consult a qualified healthcare provider. This ratio is only one part of a full lung function test.