Normal findings of spirometry are FEV/FVC ratio of greater than 0.70 and both FEV and FVC above 80% of predicted value. If lung volumes are performed, TLC above 80% of predictive value is normal. Diffusion capacity above 75% of predicted value is considered normal as well.

What are normal PFT results?

Pulmonary function testNormal value (95 percent confidence interval)FEV180% to 120%FVC80% to 120%Absolute FEV1 /FVC ratioWithin 5% of the predicted ratioTLC80% to 120%

How much lung capacity is normal?

Among healthy adults, the average lung capacity is about 6 liters. Age, gender, body composition, and ethnicity are factors affecting the different ranges of lung capacity among individuals.