Ounce


The ounce is a unit of mass, weight, or volume used in most British derived customary systems of measurement. The common avoirdupois ounce is of a common avoirdupois pound; this is the United States customary and British imperial ounce. It is primarily used in the United States to measure packaged foods and food portions, postal items, areal density of fabric and paper, boxing gloves, and so on; but sometimes also elsewhere in the Anglosphere.
Besides the common ounce, several other ounces are in current use:
Historically, a variety of different ounces measuring mass or volume were used in different jurisdictions by different trades.

Etymology

Ounce derives from Latin as ynsan or yndsan from an unattested Vulgar Latin form with ts for c before i and second into Middle English through Anglo-Norman and Middle French. The abbreviation oz came later from the cognate Italian word onza.
Inch comes from the same Latin word, but differs because it was borrowed into Old English and underwent i-mutation or umlaut and palatalization.

Definitions

Historically, in different parts of the world, at different points in time, and for different applications, the ounce has referred to broadly similar but still slightly different standards of mass.
Variant
International avoirdupois ounce28.349523125437.5
International troy ounce31.1034768480
Apothecaries' ounce31.1034768480
Maria Theresa ounce28.0668
Spanish ounce 28.75
French ounce 30.59
Portuguese ounce 28.69
Roman/Italian ounce 27.4
Dutch metric ounce 100
Dutch ounce 30
Chinese metric ounce 50
English Tower Ounce29.16450

Currently in use

International avoirdupois ounce

The international avoirdupois ounce is defined as exactly 28.349523125 g under the international yard and pound agreement of 1959, signed by the United States and countries of the Commonwealth of Nations.
In the avoirdupois system, sixteen ounces make up an avoirdupois pound, and the avoirdupois pound is defined as 7000 grains; one avoirdupois ounce is therefore equal to 437.5 grains.
The ounce is still a standard unit in the United States. In the United Kingdom it ceased to be a legal unit of measure in 2000, but is still in general usage on an informal basis. In addition it is the normal measure for portion sizes in British restaurants.

International troy ounce

A troy ounce is equal to 480 grains. Consequently, the international troy ounce is equal to exactly 31.1034768 grams. There are 12 troy ounces in the now obsolete troy pound.
Today, the troy ounce is used only to express the mass of precious metals such as gold, platinum, palladium, rhodium or silver. Bullion coins are the most common products produced and marketed in troy ounces, but precious metal bars also exist in gram and kilogram sizes.
For historical measurement of gold,
Some countries have redefined their ounces in the metric system. For example, the German apothecaries ounce of 30 grams, is very close to the previously widespread Nuremberg ounce, but the divisions and multiples come out in metric.
In 1820, the Dutch redefined their ounce as 100 grams. Dutch amendments to the metric system, such as an ons or 100 grams, has been inherited, adopted, and taught in Indonesia beginning in elementary school. It is also listed as standard usage in Indonesia's national dictionary, the Kamus Besar Bahasa Indonesia, and the government's official elementary-school curriculum.

Historical

Apothecaries' ounce

The obsolete apothecaries' ounce equivalent to the troy ounce, was formerly used by apothecaries.

Maria Theresa ounce

"Maria Theresa ounce" was once introduced in Ethiopia and some European countries, which was equal to the weight of one Maria Theresa thaler, or 28.0668 g. Both the weight and the value are the definition of one birr, still in use in present-day Ethiopia and formerly in Eritrea.

Spanish ounce

The Spanish pound was 460 g. The Spanish ounce was of a pound, i.e. 28.75 g.

Tower ounce

The Tower ounce of 450 grains was used in the English mints, the principal one being in the Tower of London. It dates back to the Anglo-Saxon coinage weight standard. It was abolished in favour of the Troy ounce by Henry VIII in 1527.

Ounce-force

An ounce-force is of a pound-force, or.
The "ounce" in "ounce-force" is equivalent to an avoirdupois ounce; ounce-force is a measurement of force using avoirdupois ounces. However, it is not necessary to identify it as such or to differentiate it in that way because there is no equivalent measure of force using troy or any other "ounce".

Fluid ounce

A fluid ounce is a unit of volume equal to about 28.4 ml in the imperial system or about 29.6 ml in the US system. The fluid ounce is sometimes referred to simply as an "ounce" in applications where its use is implicit, such as bartending.

Other uses

Fabric weight

Ounces are also used to express the "weight", or more accurately the areal density, of a textile fabric in North America, Asia or the UK, as in "16 oz denim". The number refers to the weight in ounces of a given amount of fabric, either a yard of a given width, or a square yard.
Fabric typeTypical weight in ounces
Organza, voile, chiffon1–3
Most cottons, wools, silks, muslin, linen4–7
Denim, corduroy, twill, velvet7–16

Copper layer thickness of a printed circuit board

The most common unit of measure for the copper thickness on a printed circuit board is ounces. It is the resulting thickness when 1 oz of copper is pressed flat and spread evenly over a one-square-foot area. This roughly equals 34.7 µm.