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 $\pounds$.


Sources