Interpretation of measured lung function values relies on reference equations to define the range of values that would be expected in otherwise healthy individuals. Reference equations for lung function can be interpreted in a way similar to pediatric growth charts and incorporate key anthropomorphic determinants of lung health: height, sex, and age. Race and ethnicity were previously included as a determinant of lung function through ethnic specific equations; however, this approach is no longer recommended because the potential harms outweigh the possible benefits. The clinical application of lung function results requires careful consideration of reference equations’ derivations and their limitations.