Currently available correlations for the effects of specimen size on the upper shelf energy (USE) were developed for relatively ductile steels and do not serve as well when the steels become embrittled. Size effects correlations were developed recently for the impact properties of less ductile HT9 to be applied to other initially more ductile steels as they lose their ductility during irradiation. These new correlations successfully predict the ductile brittle transition temperature (DBTT) and USE of full-size Charpy specimens based on subsize specimen data. The new DBTT and the USE correlations were tested against published experimental data on other ferritic steels and shown to perform successfully at lower USE, particularly when both notched and precracked specimens as well as notched-only specimens were employed.