Definition:Avoirdupois

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Definition

The avoirdupois system is one of the three imperial systems of measurement of mass.

Its units are defined as follows:


Grain

The grain is the imperial unit of mass which is used as the basis of all three of the imperial weight systems.

\(\ds \) \(\) \(\ds 1\) grain
\(\ds \) \(=\) \(\ds \dfrac 1 {437 \cdot 5}\) ounce avoirdupois
\(\ds \) \(\approx\) \(\ds 64 \cdotp 8\) milligrams


Dram

The dram is an avoirdupois unit of mass.

\(\ds \) \(\) \(\ds 1\) dram
\(\ds \) \(=\) \(\ds 27 \cdotp 34375\) grains
\(\ds \) \(=\) \(\ds \dfrac 1 {16}\) ounce avoirdupois
\(\ds \) \(\approx\) \(\ds 1 \cdotp 77\) grams


Ounce

\(\ds \) \(\) \(\ds 1\) 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.


Pound

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)


Stone

\(\ds \) \(\) \(\ds 1\) stone
\(\ds \) \(=\) \(\ds 14\) pounds avoirdupois
\(\ds \) \(=\) \(\ds 224\) ounces avoirdupois
\(\ds \) \(\approx\) \(\ds 6 \, 350 \cdotp 29318\) grams

The gram equivalent is exact.


Quarter

\(\ds \) \(\) \(\ds 1\) quarter
\(\ds \) \(=\) \(\ds 2\) stone
\(\ds \) \(=\) \(\ds 28\) pounds avoirdupois
\(\ds \) \(\approx\) \(\ds 12 \cdotp 7\) kilograms


Hundredweight

\(\ds \) \(\) \(\ds 1\) hundredweight
\(\ds \) \(=\) \(\ds 4\) quarters
\(\ds \) \(=\) \(\ds 8\) stone
\(\ds \) \(=\) \(\ds 112\) pounds avoirdupois
\(\ds \) \(\approx\) \(\ds 50 \cdotp 8\) kilograms


Ton

The ton is an avoirdupois unit of mass.

\(\ds \) \(\) \(\ds 1\) ton
\(\ds \) \(=\) \(\ds 20\) hundredweight
\(\ds \) \(=\) \(\ds 80\) quarters
\(\ds \) \(=\) \(\ds 160\) stone
\(\ds \) \(=\) \(\ds 2240\) pounds avoirdupois
\(\ds \) \(\approx\) \(\ds 1016\) kilograms
\(\ds \) \(\approx\) \(\ds 1 \cdotp 016\) tonnes


Also see


Linguistic Note

The word avoirdupois derives from the Norman French word whose literal translation is goods (that is property, or things owned) of weight.

The avoir part also means to have in modern French, and derives from the Latin habere.

It is pronounced something like av-wah-doo-pwah, although Francophones will be aware that there are further subtleties to this.


Sources