The Roman imperial money system was based on the metal value of coins in , silver and bronze. The coins were:

aureus (1/42 of a pound of silver) equal to 25 denarii, 400 asses

denarius (1/84 of a pound of silver) equal to 16 asses

sesterce (brass) equal to 4 asses

dupondius (brass) equal to 2 asses

as (copper) The as was halved and quartered under Augustus.
Later emperors debased the coinage and caused successive economic disturbances until Diocletian reformed the system by introducing new standard weight aurei and denari. New copper coins were also circulated but their contemporary names are not known.

aureus Maximian

denarius Carausias

sesterce Marcus Aurelius

dupondius Antoninus