A legion was organized into ten cohorts, each of which comprised six centuries, with a century further made up of ten squads (contubernia); the exact size of the Imperial legion, which is most likely to have been determined by logistics, has been estimated to range from 4,800 to 5,280.
En legion blev organiseret i ti kohorter, der hver omfattede seks centurier, som hver igen bestod af mindre delinger (romersk latin: contubernia); den nøjagtige størrelse af den kejserlige legion, som sandsygligvis var mest begrænset i størrelse af logistik, er blevet anslået til at variere fra 4.800 til 5.280.