Definition:Roman Weights and Measures/Mass

Definition

The Roman units of mass are as follows:

$1$ calcus $= \dfrac 1 8$ scrupulus.

Its value in modern units is estimated to be approximately $2.2$ grains, or approximately $0.14$ grams.

$1$ siliqua $= \dfrac 1 6$ scrupulus $= \dfrac 1 {144}$ uncia.

Its value in modern units is estimated to be approximately $2.9$ grains, or approximately $0.19$ grams.

Its modern equivalent is the carat.

$1$ scrupulus $= \dfrac 1 {24}$ uncia $= 8$ calci.

Its value in modern units is estimated to be approximately $17.6$ grains, or approximately $0.14$ grams.

$1$ uncia $= \dfrac 1 {12}$ libra $= 24$ scrupuli.

Its value in modern units is estimated to be approximately $423$ grains or $27.4$ grams.

$1$ libra $= 12$ unciae.

Its value in modern units is estimated to be approximately $5 \, 076$ grains or $329$ grams.