This study is based on a general interior lighting installation and discusses the relation between veiling luminance and the unified glare rating. Through curve fitting and a derived formula, a transfer function between veiling luminance and the unified glare rating is generated. This result connects disability glare and discomfort glare within a finite range, where the relation between them is almost linearly dependent. This transfer function has a high accuracy as shown by a comparison between the calculated results and the original data, and is the first to provide a connection between disability glare and discomfort glare.