Massa Romeinse gewichten waren gebaseerd op de libra en het twaalfde deel daarvan de uncia (twaalfde).
De eerste tabel geeft de onderverdeling van de libra: {| class="wikitable" style="text-align:right;" !rowspan="2" valign="top" | Naam || colspan="3" | Gewicht |- !libra||uncia|| gram |- | align="left" ||| 1/12 || 1 ||27,92 |- | align="left" | of || 1/8 ||3/2|| 41,88 |- | align="left" ||| 1/6 || 2 || 55,84 |- | align="leftt" | of || 1/4 ||3 || 83,75 |- | align="left" ||| 1/3 || 4 || 111,67 |- | align="left" ||| 5/12 ||5 || 139,59 |- | align="left" | of ||1/2 || 6 || 167,51 |- | align="left" | septunx|| 7/12 || 7 || 195,43 |- | align="left" | of || 2/3 || 8 || 223,34 |- | align="left" ||| 3/4 ||9 || 251,26 |- | align="left" | || 5/6 ||10 ||279,18 |- | align="left" |deunx || 11/12 || 11 || 307,10 |- style="background-color:#ccddff" | align="left" | of || 1 || 12 || 335,02
De tweede tabel geeft de onderverdeling van de uncia. {| class="wikitable" style="text-align:right;" !rowspan="2" valign="top" |Naam || colspan="2" | Gewicht |- !uncia|| gram |- | align="left" ||| 1/144 || 0,19 |- | align="left" ||| 1/48 || 0,57 |- | align="left" ||| 1/24 || 1,14 |- | align="left" ||| 1/12 || 2,27 |- | align="left" ||| 1/6 || 4,54 |- | align="left" ||| 1/4 || 6,82 |- | align="left" ||| 1/3 || 9,09 |- | align="left" ||| 1/2 || 13,96 |- style="background-color:#ccddff" | align="left" ||| 1 || 27,92
Gewichten