Ounces (oz)
An ounce (oz) is a unit of mass primarily used in the United States and UK customary systems. One avoirdupois ounce equals exactly 28.349523125 grams as defined by NIST. This measure is commonly employed in food labeling, postal services, and retail [nist-sp-811].
Origin
The ounce originated from the Roman 'uncia,' a twelfth part of the Roman pound. The avoirdupois ounce was standardized in the 19th century by the international yard and pound agreement of 1959 to unify US and British definitions [nist-sp-811].
Worldwide Use
Ounces are widely used in the US for weight measurement in grocery, postal, and manufacturing sectors. The UK uses ounces in certain contexts like precious metals and food portions. Most other countries prefer grams and kilograms per SI [nist-sp-811].
Common References
- A standard chocolate bar weighs about 1.5 oz
- A US fluid ounce of water weighs approximately 1.04 oz
- An average apple weighs roughly 6 oz
- A pack of butter usually contains 4 oz per stick
- Postage rates often calculate cost per ounce