Ounce

This article is about the unit of measure. Ounce is also another name for the snow leopard.

The ounce is the name for a number of different units of mass (oz), and also of two units of fluid volume (fl oz) and of one unit of force, the ounce-force (ozf). See Imperial system of units and U.S. customary units for more about the frameworks within which these units are defined.

avoirdupois ounce defined by the avoirdupois system of mass (see pound (mass)). There are 16 ounces in the avoirdupois pound. The avoirdupois ounce is approximately 28.35 gram (or 437.50 grains).
troy ounce defined by the troy system of mass. In troy weight, there are 12 ounces in a troy pound, and a troy pound is 5760 grains (about 373.24 g), rather than the 7000 grains (about 453.59 g) in the avoirdupois pound. Note: at roughly 31.104 g (or 480 grains), the troy ounce is about 10 per cent more than the more common avoirdupois ounce of 28.35 g (or 437.50 grains). There are approximately 14.5833 troy ounces in an avoirdupois pound. These troy ounces are now used only when weighing precious metals like gold, platinum and silver. One ounce of gold is always 31.1 g. "Maria Theresa ounce" was once introduced in Ethiopia and some European countries, which was equal to 31.1025 g.
apothecaries' ounce defined by the now-obsolete apothecaries' system of mass. This ounce was the same size as the troy ounce, and its symbol was ℥ (2125).
The fluid ounce unit of volume also exists in the two versions of 28.41 ml (Imperial) and 29.57 ml (U.S.).
The ounce-force (see pound-force) is the force exerted by a mass of 1 oz avoirdupois at the standard acceleration of gravity, usually borrowing the value that is official for defining kilograms-force, 9.80665 m/s². Thus 1 ozf is approximately 278.0 millinewton.
ounce of hide/leather thickness is measured by a gauge in ounces or millimeters. An ounce equals inch in this application. Source: p. 17 Leather Facts 3rd Edition, 1994. Published by New England Tanners Club.

For historical measurement of gold,

a fine ounce is a troy ounce of 99.5% ("995") pure gold
a standard ounce is a troy ounce of 22 carat gold, 91.66% pure (11 "fine ounces" plus one ounce of alloy material to make one troy pound.

Metric redefinitions

Some countries have redefined their ounces to fit in with the metric system.

The Dutch have redfined their ounce (in Dutch, ons) as 100 g (much more than a traditional ounce). This was adopted along with the introduction of the metric system together with a redefinition of the Dutch pound (pond) as 1 kg. (Though the ons of 100 g remains in informal usage, this pond as a kilogram has fallen by the wayside, replaced by the metric pound of 500 g adopted in other countries.)

The Chinese used to have a traditional ounce known as a tael (in Chinese, 两 liǎng) of varying value. This has now been rounded off to 50 grams.

External links

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