Definition:FPS/Pound

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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

 $\displaystyle$  $\displaystyle 1$ pound avoirdupois $\displaystyle$ $=$ $\displaystyle 16$ ounces avoirdupois $\displaystyle$ $=$ $\displaystyle 7 \, 000$ grains $\displaystyle$ $=$ $\displaystyle 453 \cdotp 59237$ grams

The gram equivalent is defined to be exact.

Apothecaries' Pound

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

Troy Pound

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

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

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 $\pounds$.