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Physical unit
Unit name ounce
Unit symbol
Physical quantity (s) Dimensions
Formula symbol
system Anglo-American system of measurement
In SI units
Named after Latin Uncia = 1/12
Derived from lb
See also: Roman numerals # fractions

An ounce ( Latin uncia , one twelfth, originally a Roman libra and a pharmacist's pound , since then usually a sixteenth of a pound , symbol ℥) is a non-metric unit of mass . The unit symbol is oz in the Anglo-American system of measurement . (from ital. onza ), the English name ounce .

Different ounces

Ordinary ounce

The common ounce ( English international avoirdupois ounce ) with the unit symbol oz. is still used in food in some English-speaking countries today. It is the equivalent of 28.35 grams .

The original (Roman) ounce was 27.2875 grams.

Pharmacist Ounce / Medicinal Weight

The apothecary ounce (English apothecaries ounce ) with the unit symbol ℥ or oz. ap. was previously used for medicines and chemicals and was the equivalent of about 31.1 grams. She was last officially in the United States (until 1971) and in the United Kingdom (until 1976).

In Württemberg the ounce was 29.80 grams and in Basel 29.815 grams.

Troy ounce

The troy ounce (English troy ounce ) with the unit symbol oz. tr. is used for precious metals . Their weight corresponds to the pharmacist's ounce (1 oz.tr. = 31.1034768 g), but only relates to the precious metal content of a coin or a bar. The mass fraction of any impurities or added metals (for hardening, often silver or copper, as with the Krugerrand ) is therefore subtracted from the total mass. The gold , silver , platinum and palladium prices are usually quoted per troy ounce.

Liquid ounce

The liquid ounce (English fluid ounce ) with the unit symbol fl oz is used in English-speaking cubic measure for liquids. The measure is used, for example, when measuring perfume or soft drinks. A fluid ounce corresponds to 1/160 of an imperial gallon in the United Kingdom and many Commonwealth of Nations (28.4131 cm³) and in the United States 1/128 of a US gallon in the US system (29.5735 cm³). It is roughly equivalent to the volume of an ordinary ounce of water. Today it is only officially in the United States.

Metric ounce

In the Netherlands and Indonesia , ons has been an unofficial but widespread unit since the switch to the metric system , equivalent to 100 g.

Definition and conversion

  • 1 oz. = 16 dr. ( Dram ) = 437.5 gr. ( Gran ) = 28.349523125 g ( grams )
  • 1 oz.ap. = 8 dr.ap. = 480 gr.
  • 1 oz. = 1 oz.ap. = 192175 oz.
  • 1 oz. = 480 gr. = 31.1034768 g (ounce for precious metals, troy ounce )
  • 192 oz. = 175 oz. = 5.44310844 kg ; Conversion factor derived therefrom oz.tr. → oz .:
  • 1 pound = 16 oz. = 7000 grain = 453.59237 grams
  • 1 troy pound = 12 oz. = 5760 grain = 240 dwt. = 373.2417216 grams

Ounces in other languages ​​and countries

Related terms are:

  • Okka: a measure in Hungary, Slavonia and Croatia.
  • Occa , Oka, Ocka: measure of measure in Wallachia
  • Okka, Oka, Occa, Ocka: Turkish trade weight
  • Uncja: Polish ounce
  • Onca, Once, Onciam Ounce
  • Onca, Onça: Spanish, Portuguese and Brazilian weights
  • Ling, Lyang (盎司): Chinese ounce
  • Wakea, Waki ​​(also Vakea, Vaki): Gold ounce in Abyssinia
  • Okkia: silver coins in Morocco
  • Ouguiya ( Arabic أوقية, DMG Ūqīya ): a measure and currency in Arabic-speaking countries


In the past, ounce was also a name for the jaguar ( Panthera onca ; Portuguese Onça ) and the Irbis ( Uncia uncia ).

See also


  • Royal Württemb. Central office for trade and commerce (ed.): The dimensions and weights of Württemberg versus the metrics of the German Empire . Publishing house of JB Metzler'schen Buchhandlung, Stuttgart 1871.

Web links

Wiktionary: ounce  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. uncĭa , Charlton T. Lewis, Charles Short, A Latin Dictionary, (English)
  2. Harald Witthöft in Lexicon of the Middle Ages . Volume 4, 1423.
  3. The measurements and weights of Württemberg versus the metrics of the German Empire.
  4. ^ Hermann Mulsow: Mass and weight of the city of Basel up to the beginning of the 19th century. Phil. Dissertation, Freiburg im Breisgau 1910, p. 69.
  5. ^ Johann Friedrich Krüger : Complete manual of the coins, measures and weights of all countries in the world. Gottfried Basse, Quedlinburg / Leipzig 1830
  6. goldreporter.de , accessed on March 17, 2017
  7. Brehm's Illustrirtes Thierleben 1st vol. Die Säugethiere , Hildburghausen 1870
  8. ^ Jakob Heinrich Kaltschmid: New and complete foreign dictionary to explain all expressions borrowed from foreign languages , 1870