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Information about Ounces

This article is about Ounce (unit of mass). For Ounce (unit of force), see Pound-force. For all other uses, see Ounce (disambiguation).
The ounce (abbreviation: oz) is the name of a unit of mass in a number of different systems, including various systems of mass that form part of English units, Imperial units, and United States customary units. Its size can vary from system to system. The most commonly used ounces used today are the international avoirdupois ounce and the international troy ounce.

The abbreviation "oz" comes from the old Italian word "onza" (now spelled oncia), meaning ounce.

The distinction between mass and weight (or force), and its development, is discussed in the article on weight.

Summary of ounce units

Following table shows different ounce units in grams (SI):
Summary of ounce units
Ounce variant Mass in grams
International avoirdupois ounce (most common)28.349 523 g
International troy ounce31.103 476 g
Apothecaries' ounceSame as international troy ounce
Maria Theresa ounce28.066 8 g
Dutch metric ounce100 g
Chinese metric ounce50 g
Tael (East Asia)Varying mass

International avoirdupois ounce

Main article: avoirdupois


An avoirdupois ounce is equal to 437.5 grains. There are 16 avoirdupois ounces in an avoirdupois pound. In 1958 the United States and countries of the Commonwealth of Nations defined the mass of the international avoirdupois pound to be 0.453 592 37 kilograms. Consequently, since 1958, the international ounce is defined to be equal to about 28.349 523 grams.

The ounce is commonly used as a unit of mass in the United States. While imperial units have been officially abolished in the United Kingdom, the ounce remains a familiar unit, especially amongst older people.

International troy ounce

Main article: Troy weight


A troy ounce (abbreviation: t oz) is equal to 480 grains. There are 12 troy ounces in a troy pound. Consequently, the international troy ounce is equal to about 31.103 476 grams.

Today, the troy ounce is used only to express the mass of precious metals such as gold, platinum or silver.

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)

Other ounces

Historically, in different parts of the world, at different points in time, and for different applications, the ounce (or its translation) has referred to broadly similar but different standards of mass (or weight, before the distinction between weight and mass developed). Some of these other ounces are described below.

Apothecaries' ounce

Main article: Apothecaries' system of mass


An 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 ℥ (U+2125).

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 Eritrea.

Metric ounces

Main article: kilogram


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

The Dutch have redefined their ounce (in Dutch, ons) as 100 grams. Also the Avoirdupois pound (in Dutch pond) was redefined to 500 grams. This was adopted along with the introduction of the metric system and remains in informal usage (mostly in cookery and groceries).

East Asia has a traditional ounce, known as a tael, of varying value. In China, it has been given a metric value of 50 grams.

References

See also

fluid ounce

External links

A pound or pound-force (abbreviations: lb, lbf, or lbf) is a unit of force. Pound is also the name of a unit of mass. One pound-force is approximately equal to the gravitational force exerted on a mass of one avoirdupois pound on the
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An ounce can be:
  • ounce, the name of a number of units of mass;
  • the ounce-force, a unit of force, 1⁄16 of the pound-force;
  • a fluid ounce, the name of a number of units of volume;
  • ounce

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units of measurement have played a crucial role in human endeavour from early ages up to this day. Disparate systems of measurement used to be very common. Now there is a global standard, the International System (SI) of units, the modern form of the metric system.
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Mass is a fundamental concept in physics, roughly corresponding to the intuitive idea of "how much matter there is in an object". Mass is a central concept of classical mechanics and related subjects, and there are several definitions of mass within the framework of relativistic
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English unit is the American name for a unit in one of a number of systems of units of measurement, some obsolete, and some still in use. In spite of the name, it does not necessarily refer to the (non-SI) system of units still in widespread, but mostly unofficial, use in England
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Imperial units or the Imperial system is a collection of units, first defined in the British Weights and Measures Act of 1824, later refined (until 1959) and reduced.
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U.S. customary units, also known in the United States as English units[1] (but see English unit) or standard units, are units of measurement that are currently used in the USA, in some cases alongside units from SI (the International System of Units
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The avoirdupois (IPA: /ˌævərdəˈpɔɪz/; French IPA: [avwɑrdypwɑ]
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weight is a measurement of the gravitational force acting on an object. Near the surface of the Earth, the acceleration due to gravity is approximately constant; this means that an object's weight is roughly proportional to its mass.
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The avoirdupois (IPA: /ˌævərdəˈpɔɪz/; French IPA: [avwɑrdypwɑ]
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A grain (symbol: gr) is a unit of mass now equal to exactly 64.79891 milligrams, in all English mass and weight systems (avoirdupois, Apothecaries’ and troy).

An avoirdupois ounce is equal to 437.5 grains, whereas a troy ounce is equal to 480 grains.
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pound or pound-mass (abbreviations: lb, ℔, lbm, or sometimes in the United States: #) is a unit of mass (sometimes called 'weight' in everyday parlance) in a number of different systems, including English units, Imperial units, and United
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19th century - 20th century - 21st century
1920s  1930s  1940s  - 1950s -  1960s  1970s  1980s
1955 1956 1957 - 1958 - 1959 1960 1961

Year 1958 (MCMLVIII
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Motto
"In God We Trust"   (since 1956)
"E Pluribus Unum"   ("From Many, One"; Latin, traditional)
Anthem
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Headquarters
(and largest city)
Official languages English
Membership 53 sovereign states
Leaders
 -  Head of the Commonwealth Queen Elizabeth II
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kilogram or kilogramme (symbol: kg) is the SI base unit of mass. The kilogram is defined as being equal to the mass of the International Prototype Kilogram (IPK), which is almost exactly equal to the mass of one liter of water.
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19th century - 20th century - 21st century
1920s  1930s  1940s  - 1950s -  1960s  1970s  1980s
1955 1956 1957 - 1958 - 1959 1960 1961

Year 1958 (MCMLVIII
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Gram
Unit sign g
Measure Mass
Base Unit Kilogram
Multiple of Base 10−3
System SI, CGS, other
Common usage Commonly used in cooking and food labeling
Examples
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Motto
"In God We Trust"   (since 1956)
"E Pluribus Unum"   ("From Many, One"; Latin, traditional)
Anthem
..... Click the link for more information.
Troy weight is a system of units of mass customarily used for precious metals, black powder, and gemstones.

Units

The Troy

Although the troy was known to exist in medieval times, it was not until 1758 that it was established as the standard unit from which other
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A grain (symbol: gr) is a unit of mass now equal to exactly 64.79891 milligrams, in all English mass and weight systems (avoirdupois, Apothecaries’ and troy).

An avoirdupois ounce is equal to 437.5 grains, whereas a troy ounce is equal to 480 grains.
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pound or pound-mass (abbreviations: lb, ℔, lbm, or sometimes in the United States: #) is a unit of mass (sometimes called 'weight' in everyday parlance) in a number of different systems, including English units, Imperial units, and United
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Gram
Unit sign g
Measure Mass
Base Unit Kilogram
Multiple of Base 10−3
System SI, CGS, other
Common usage Commonly used in cooking and food labeling
Examples
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GOLD refers to one of the following:
  • GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade).
  • GOLD (parser) is an open source BNF parser.

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4, 5, 6
(mildly basic oxide)
Electronegativity 2.28 (scale Pauling)
Ionization energies 1st: 870 kJ/mol
2nd: 1791 kJ/mol
Atomic radius 135 pm
Atomic radius (calc.
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Silver (IPA: /ˈsɪlvə(ɹ)/) is a chemical element with the symbol Ag (Latin: argentum) and atomic number 47.
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GOLD refers to one of the following:
  • GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade).
  • GOLD (parser) is an open source BNF parser.

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For other uses of the word "carat", see Carat.


The carat (abbreviation ct or K) is a measure of the purity of gold and platinum alloys.
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An alloy is a homogeneous hybrid of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. The resulting metallic substance usually has different properties (sometimes substantially different) from those of its components.
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The apothecaries' system of mass is an obsolete system formerly used by apothecaries (now called pharmacists or chemists) in English-speaking countries. The system is related to the English avoirdupois and troy systems, as they use the same mass for a grain.
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