The microstructures of cold work steel includes 16% primary carbides, 16% retained austenite and martensite after oil quenching or gas quenching. The carbide volume fraction should be determined by chemical extraction or metallographic methods. Adequate X-ray diffraction peak resolution for carbide peak identification is required to avoid overlapping carbide peaks in the retained austenite measurement [4]. Das et al. [5] conducted sub-zero treated AISI D2 experiments and demonstrated that retained austenite can be reduced by cold treatment. This paper compares the retained austenite amount determination in the quenched and tempered SKD11 tool steels between the metallographic and X-ray diffraction measurement methods.