The ships of the class varied slightly in dimensions. "Littorio" and "Vittorio Veneto" were long between perpendiculars and long overall, while "Roma" and "Impero" were long overall. All four ships had a draft of and a beam of . "Littorio" displaced as designed and at full load. "Vittorio Veneto" displaced and , respectively. "Roma"s displacement increased slightly as compared to the other ships, to and , respectively. As "Impero" was not completed, her final displacement is unknown. As built, the ships were fitted with bulbous bows to increase their speed, but they were found to cause serious vibration, which forced a modification to the bow.