Interstitial lung diseases (ILDs) encompass a large group of diseases with great variability in clinical severity and behavior. If computed tomography (CT) plays a key role in the detection and characterization of ILD, visual CT analysis is subjective and prone to inter- and intraobserver variability. Measurements in ILD may seem unrealistic as the disease may be diffuse, heterogeneous, and characterized by complex and sometimes subtle patterns. However, there has been growing interest in the recent years for the development of quantitative imaging biomarkers that could help the radiologist tracking disease progression and response to treatment. This chapter will review the reasons why measurements in ILD are important, and the tools available for the radiologists, to address directly or indirectly the extent and severity of the disease.