# Definition:Ounce

## Definition

The ounce is a unit of mass whose precise value depends upon which scale is used.

### Ounce Avoirdupois

 $\ds$  $\ds 1$ ounce avoirdupois $\ds$ $=$ $\ds 16$ drams $\ds$ $=$ $\ds 437 \cdotp 5$ grains $\ds$ $=$ $\ds 28 \cdotp 34952 \, 3125$ grams $\ds$ $=$ $\ds 0 \cdotp 02834 \, 95231 \, 25$ kilograms

The gram / kilogram equivalent is defined to be exact.

### Apothecaries' Ounce

The apothecaries' ounce is an apothecaries' unit of mass.

 $\ds$  $\ds 1$ apothecaries' ounce $\ds$ $=$ $\ds 8$ drachms $\ds$ $=$ $\ds 24$ scruples $\ds$ $=$ $\ds 480$ grains $\ds$ $=$ $\ds 1$ troy ounce $\ds$ $=$ $\ds 31 \cdotp 1$ grams

### Troy Ounce

 $\ds$  $\ds 1$ troy ounce $\ds$ $=$ $\ds 20$ pennyweight $\ds$ $=$ $\ds 480$ grains $\ds$ $=$ $\ds 1$ apothecaries' ounce $\ds$ $\approx$ $\ds 31 \cdotp 1$ grams

### Uncia (Roman Ounce)

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

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

## Symbol

$\mathrm {oz.}$

The symbol for the ounce is $\mathrm {oz.}$

The $\LaTeX$ code for $\mathrm {oz.}$ is \mathrm {oz.} .

## Linguistic Note

The word ounce derives from the Latin uncia, meaning $\dfrac 1 {12}$ part (of an as).

Despite the gradual migration to the metric system, the word ounce still lives on as a rhetorical flourish for something small, for example:

If you only had an ounce of sense you would understand that ...