# Definition:FPS/Pound

## Definition

The pound is the FPS unit of measurement of mass, which has a number of different standards.

The most common standard is for it to be defined in kilograms to be exactly $0.453 \, 592 \, 37 \ \mathrm{kg}$.

### Pound Avoirdupois

The pound is an avoirdupois unit of mass.

It is defined as being exactly $453 \cdotp 59237$ grams.

 $\ds$  $\ds 1$ pound avoirdupois $\ds$ $=$ $\ds 16$ ounces avoirdupois $\ds$ $=$ $\ds 7 \, 000$ grains $\ds$ $=$ $\ds 453 \cdotp 59237$ grams $\quad$ (exact) $\ds$ $=$ $\ds 0 \cdotp 45359237$ kilograms $\quad$ (exact)

### Apothecaries' Pound

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

 $\ds$  $\ds 1$ apothecaries' pound $\ds$ $=$ $\ds 12$ apothecaries' ounces $\ds$ $=$ $\ds 5 \, 760$ grains $\ds$ $=$ $\ds 373 \cdotp 24$ grams $\ds$ $=$ $\ds 1$ troy pound

### Troy Pound

 $\ds$  $\ds 1$ troy pound $\ds$ $=$ $\ds 12$ troy ounces $\ds$ $=$ $\ds 5 \, 760$ grains $\ds$ $=$ $\ds 1$ apothecaries' pound $\ds$ $\approx$ $\ds 373 \cdotp 24$ grams

### Libra (Roman Pound)

$1$ libra $= 12$ unciae.

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

## Symbol

$\mathrm {lb}$

The symbol for the pound is $\mathrm {lb}$.

Its $\LaTeX$ code is \mathrm {lb} .

This derives from the libra (Roman pound) from which the pound evolved.

It always needs to be distinguished from the pound sterling, whose symbol is $\pounds$.