Evaluation methodology of standard Charpy impact properties in the cleavage fracture region from subsized specimen test results has been demonstrated. It consists of 1) subsized Charpy V-notch impact tests; 2) tensile tests at various temperatures and strain rates; and 3) three dimensional finite element method (FEM) simulations of the impact test with a temperature and strain rate dependent constitutive equation and a cleavage fracture model that is based on a stress-critical area criteria. The standard impact properties of a ferritic/martensitic steel (JFMS) in the cleavage facture region have been evaluated, and there was reasonable agreement between simulations and experimental results.