in gold:
Double Aureus (rare, with emperor wearing
radiate crown)
Aureus = 25
denari
ca. 2 cm, ca. 7-7.8 gr
Half Aureus (quinarius) = 12.5
denari
rare
in silver:
Cistophorus = 3
denari
ca. 2.8 cm, ca. 10.1-10.5 gr
good silver
later
only copper
with
more or less silver coating
Antoninianus = 2
denari
ca. 2.3 cm, ca. 5.2-5.4 gr or often much less, emperor wears radiate
crown
Denarius = 16
asses
ca. 1.7-2.0 cm, ca. 3.3 gr
Half Denarius (quinarius) = 8
asses
ca. 1.5 cm, ca 1.4 gr
in brass:
Double Sestertius = 8
asses
ca. 3.7 cm, ca. 50 gr or often less, emperor wears radiate crown
Sestertius = 4
asses:
ca. 3.0-3.8 cm, ca. 20-30 gr
Dupondius = 2
asses:
ca. 2.6-3.0 cm, ca. 10-12 gr, emperor wears radiate crown after Nero
Semis = half
as
ca. 2,0 cm, ca. 3-6 gr, emperor wears sometimes radiate crown
in copper / bronze:
As
ca. 2.6-3.0 cm, ca. 10-12 gr
Quadrans = quarter
as
ca. 1.7 cm, ca. 3 gr
Please note that not all
denominations were in use
throughout
the full period.
Also there was a tendency of inflation
that reduced
both
the size and the content of precious metal over the centuries. E.g.
late
Antoniniani towards the end of the third century AD contain hardly any
silver and often look like bronze coins.
Along this line the lower denominations
like the
quadrans
and the semis became obsolete along the way, while the double pieces
like
Antoninianus or Double Sestertius were introduced only in the third
century.
And of course the weights and sizes given
are average
values only.