# FEV₁/FVC Ratio (Obstructive vs Restrictive Pattern) Compute FEV₁/FVC and classify obstructive (<70% GOLD) vs restrictive (normal ratio, reduced FVC) patterns, with the ATS/ERS LLN caveat. Not medical advice. > Canonical page: https://elysiatools.com/en/tools/fev1-fvc-ratio - **Category:** Health - **Keywords:** fev1, fvc, fev1/fvc ratio, spirometry, obstructive, restrictive, copd, asthma, pulmonary function test, gold criteria, airflow limitation ## Overview The FEV₁/FVC Ratio Calculator computes the proportion of forced vital capacity exhaled in the first second of spirometry to help identify obstructive or restrictive ventilatory patterns. Using GOLD criteria and ATS/ERS spirometry standards, it evaluates airflow limitation based on your measured FEV₁, FVC, and optional predicted FVC values. ## Inputs - **FEV₁ — Forced Expiratory Volume in 1s (L)** (number): Forced expiratory volume in 1 second, liters. - **FVC — Forced Vital Capacity (L)** (number): Forced vital capacity, liters. - **Predicted FVC (L, optional)** (number): Predicted FVC in liters (e.g., from the vital-capacity-estimator tool); enables %FVC and restrictive-pattern assessment. - **Decimal Places** (number) ## When to use - Evaluating spirometry reports to check for airway obstruction such as COPD or asthma. - Screening for possible restrictive pulmonary defects when FVC is reduced alongside a normal FEV₁/FVC ratio. - Comparing calculated spirometric ratios against standard clinical thresholds during pulmonary research or study. ## How it works - Enter measured Forced Expiratory Volume in 1 second (FEV₁) and Forced Vital Capacity (FVC) in liters. - Optionally provide the predicted FVC in liters to calculate the percentage of predicted FVC (%FVC). - Set the desired decimal precision for the calculated percentage values. - The tool divides FEV₁ by FVC and classifies the ventilatory pattern using the GOLD 70% threshold and relative FVC levels. ## Use cases - Classifying spirometry test results into obstructive, restrictive, or normal ventilatory patterns. - Assessing percentage of predicted FVC alongside ratio metrics for comprehensive respiratory reports. - Academic training and case practice for interpreting pulmonary function test (PFT) parameters. ## Frequently asked questions ### What is considered an obstructive pattern? An FEV₁/FVC ratio below 70% (0.70) under GOLD criteria indicates an obstructive ventilatory defect. ### How is a restrictive pattern suggested on spirometry? A preserved or high FEV₁/FVC ratio (≥70%) combined with a reduced FVC (<80% predicted) suggests restriction, requiring total lung capacity (TLC) testing to confirm. ### Why is predicted FVC optional? FEV₁/FVC calculation only requires measured FEV₁ and FVC, but predicted FVC is necessary to assess whether FVC is abnormally low. ### What is the ATS/ERS LLN caveat? A fixed 70% cutoff can overdiagnose obstruction in elderly individuals and underdiagnose it in young adults compared to the Lower Limit of Normal (LLN). ### Does this tool provide a formal medical diagnosis? 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