Lung Capacity Calculator
Calculate TLC, FVC, FEV1 & Respiratory Function
Calculate predicted lung volumes and capacities based on age, height, gender, and ethnicity using standardized prediction equations.
Personal Information
For ethnicity-specific corrections
About Lung Volumes
TLC: Total lung capacity - maximum air lungs can hold
FVC: Forced vital capacity - maximum air exhaled forcefully
FEV1: Volume exhaled in first second of forced breath
RV: Residual volume - air remaining after maximal exhalation
Normal Ranges
FEV1/FVC Ratio:
Normal: >70% (>0.70)
Obstruction: <70%
RV/TLC Ratio:
Normal: 20-35%
Hyperinflation: >35%
Important Note
These are predicted values based on population norms. Actual lung function should be measured via spirometry. Consult a healthcare professional for proper diagnosis.
Understanding Lung Volumes
Lung volumes and capacities are key measurements of respiratory function used to diagnose and monitor lung diseases.
Key Volumes:
- TLC: Total volume of air in lungs after maximal inspiration
- VC: Maximum volume that can be exhaled after maximal inspiration
- RV: Volume remaining in lungs after maximal exhalation
- FRC: Volume in lungs at end of normal exhalation
- IC: Maximum volume that can be inhaled from resting level
Clinical Significance
Abnormal lung volumes can indicate various respiratory conditions:
- Reduced FEV1/FVC (<70%): Obstructive diseases (COPD, asthma)
- Reduced TLC and VC: Restrictive diseases (fibrosis, obesity)
- Increased RV/TLC: Air trapping (emphysema)
- Reduced FVC with normal ratio: Restrictive pattern
- Normal predicted values: Vary by age, height, gender, ethnicity
Spirometry Patterns
Normal Pattern:
- FEV1/FVC > 70%
- FVC > 80% predicted
- FEV1 > 80% predicted
- TLC within normal range
Obstructive Pattern:
- FEV1/FVC < 70%
- Reduced FEV1
- Normal or increased TLC
- Increased RV/TLC ratio
- Examples: COPD, asthma
Restrictive Pattern:
- FEV1/FVC normal or high
- Reduced TLC (<80%)
- Reduced FVC
- Proportionally reduced FEV1
- Examples: Fibrosis, obesity
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