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Fev1/Fvc Ratio Calculator

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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.
See also  BOD Load Calculator

Tip:
Always use the same units (liters or milliliters) for FEV1 and FVC.

General Reference Table

TermWhat It MeansTypical Example
FEV1Air blown out in 1 second3.0 liters
FVCTotal air blown out4.0 liters
Normal RatioHealthy adults75%–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

Q2: What does a low ratio mean?

A: A lower-than-normal ratio often suggests airway blockage, which can happen in diseases like asthma or chronic obstructive pulmonary disease (COPD).

Q3: Should I rely on this alone for diagnosis?

A: No. Always consult a qualified healthcare provider. This ratio is only one part of a full lung function test.

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