Work injury compensation and pensions are often determined according to medical disability rating scales attributing a percentage to each impaired body part or function. Incorporated into central medical–administrative networks of committees and examinations, these produce disability as a calculable space. This article examines the specific case of the Israeli National Insurance regulations regarding work injuries of 1956 and analyzes the shifted order they set. Looking at this system in the specific historical context of transition from the British Mandate workmen’s compensation system to the “disability percentages” system, provides insight into the process of structuring and stabilizing durable numerical forms and the production of centralized government. Drawing on conceptualizations regarding the sociotechnical role of classification systems, I contend that through encoding and calculating classifications of disability, heterogeneity is eliminated and an ordering based on physiology is “black boxed,” illustrating the importance of technoscientific formations in structuring the “medical model of disability.”