ABSTRACTYUE PENG. Metrological evaluation of size specifications in ISO 14405-1. (Under the direction of DR. EDWARD P. MORSE)The international standard ISO 14405-1 was released in 2010 as part of the geometrical product specifications (GPS) of the ISO system. This document provides standardized definitions of linear sizes. Most notably, it has expanded the linear size specifications from the ISO default specification operator — the two-point size — to 14 types of sizes. This richer scope of size specifications is intended to assist the geometric dimensioning and tolerancing (GD&T) of products.To clarify the semantics of the size specifications and to understand their application in conformance assessment, this thesis evaluated 8 of the sizes, offering computational algorithms, experimental data processing, numerical results and interpretations of results. Two types of features, a cylinder and a constant width shaped part are covered as physical examples for the evaluations of the sizes. The latter feature provides insights into the conformance of some traditional measurement methods of two-point size to the standard, for example measurements with vernier calipers. Geometric evaluations of these features were carried out on data sets collected with coordinate measuring machines (CMMs). The sources of uncertainty in the calculations of some sizes were analyzed, including uncertainty introduced by individual measured points and influence of sampling density.