This paper reports on the development of a practical tool for determining minimum machining depths required after heat treatment of ASTM Grade 2 titanium alloys. Mechanical properties are adversely affected by the brittle alpha-case that develops when titanium and its alloys are exposed to oxygen at elevated temperatures. This layer is normally removed by machining prior to putting the component into service. The exact depth of material that is required to be removed is dependent on the combined time and temperature of any prior heat treatment. This paper presents a study of oxygen diffusion in ASTM Grade 2 titanium alloy that was performed to quantify the rate of alpha-case formation. A generalized method of predicting the depth of alpha-case is discussed and a nomogram has been developed and presented as a tool for determining the minimum amount of material that needs to be removed.