Definition:Troy
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Definition
The troy 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 |
Pennyweight
The pennyweight is a troy unit of mass.
| \(\ds \) | \(\) | \(\ds 1\) | pennyweight | |||||||||||
| \(\ds \) | \(=\) | \(\ds 24\) | grains | |||||||||||
| \(\ds \) | \(\approx\) | \(\ds 1 \cdotp 56\) | grams |
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 |
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 |
Talent
| \(\ds \) | \(\) | \(\ds 1\) | talent | |||||||||||
| \(\ds \) | \(=\) | \(\ds 75\) | troy pounds | |||||||||||
| \(\ds \) | \(=\) | \(\ds 900\) | troy ounces |
Also see
Historical Note
The troy (system of) weights is used, although rarely now, for precious metals.
It descends from the system of weights used by the Romans.
Although in some cases bearing the same names as their imperial counterparts, the actual units themselves were subtly different in size.
The units do in fact coincide with the units of the same name in the apothecaries' system.