What kind of breast plate did Roman soldiers wear? A Roman soldier’s breastplate is described by Polybius (vi.23) as “a bronze plate, measuring a span every way, which they wear on their breasts and call a heart-guard (kardiophulax).”

Body armor of the principes (heavy infantry), hastati (front-line soldiers), and triarii (veterans) consisted of only a 20cm square breastplate, called a heart guard (pectorale), and one greave. The one greave was worn on the left leg, the leg that was exposed during battle.

Roman soldiers wore a loose-fitting, sleeve-less tunic made from wool or linen that ended right above the knee, a belt (cingulum), caligae (heavy-soled hobnailed military sandal boots), and a coat that also functioned as a blanket.

Roman military personal equipment was produced in large numbers to established patterns, and used in an established manner. These standard patterns and uses were called the res militaris or disciplina .

Roman soldier's physical size I recall reading that exhumed roman soldiers from the imperial expansion period were 5'7 to 5'9 on average. The reasoning was that being drafted/enlisted at 13 to 15 and being fed a superior protein diet the soldiers were larger than an average person in the empire.