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Convert oz to kg

Please provide values below to convert ounce [oz] to kilogram [kg], or vice versa.

From: ounce
To: kilogram


Definition: An ounce (symbol: oz) is a unit of mass in the imperial and US customary systems of measurement. The avoirdupois ounce (the common ounce) is defined as exactly 28.349523125 grams and is equivalent to one sixteenth of an avoirdupois pound.

History/origin: The origin of the term ounce stems from the Roman uncia, which means a "twelfth part," and the use of a standardized copper bar which defined both the Roman pound and foot. The copper bar was divided into twelve equal parts, called unciae. This relationship between the Roman pound and foot eventually contributed to the uncia being the basis of the modern inch as well as the common ounce. The ounce has been used as a standard of mass throughout history for different applications and with different definitions. Examples include the Dutch metric ounce (100g), French ounce (30.59g), and the Spanish ounce (28.75g), among others. The current definition of the ounce, the international avoirdupois ounce was adopted in 1959.

Current use: The ounce is still a standard unit of mass in the US customary system of measurement. It is mostly used in the United States for measuring packaged food products, food portions, and postal items, among other things. The ounce is still used in some other countries around the world that have roots in British history and culture. Due to metrication, the United Kingdom (UK) no longer officially uses the ounce. It is however, still used in some settings in the UK, such as restaurants.


Definition: A kilogram (symbol: kg) is the base unit of mass in the International System of Units (SI). It is currently defined as being equal to the mass of the International Prototype of the Kilogram (IPK), a cylinder made of a platinum-iridium alloy.

History/origin: The name kilogram was derived from the French "kilogramme," which in turn came from adding Greek terminology meaning "a thousand," before the Late Latin term "gramma" meaning "a small weight."

Unlike the other SI base units, the kilogram is the only SI base unit with an SI prefix. SI is a system based on the meter-kilogram-second system of units rather than a centimeter-gram-second system. This is at least in part due to the inconsistencies and lack of coherence that can arise through use of centimeter-gram-second systems, such as those between the systems of electrostatic and electromagnetic units.

The kilogram was originally defined as the mass of one liter of water at its freezing point in 1794, but was eventually re-defined, since measuring the mass of a volume of water was imprecise and cumbersome. The current definition of a kilogram, defined as being equal to the mass of a physical prototype, is still imperfect. This is evidenced by the fact that the mass of the original prototype for the kilogram now weighs 50 micrograms less than other copies of the standard kilogram.

Current use: As a base unit of SI, the kilogram is used globally in all fields and applications, with the exception of countries like the United States, where the kilogram is used in many areas, at least to some extent (such as science, industry, government, and the military) but typically not in everyday applications.

Possible future changes: The definition of some SI base units may change in the near future. The International Committee for Weights and Measures (CIPM) has proposed re-definition of some of the SI base units in an attempt to further improve the system. Although the definitions of some units may change, the actual size of the units would remain the same; the change in definition will not have much, if any, effect on the daily use of these units.

The kilogram is one of the SI units being considered for re-definition. The current definition is based on the mass of a physical prototype which has been seen to change over time. Although the measured change is relatively small (50 micrograms), having a standard of measurement that changes at all is undesirable. As such, the proposed re-definition of the kilogram seeks to make the kilogram a measurement based on a constant of nature, rather than a physical standard that is subject to change.

If the formal vote to change the definition passes, the kilogram will instead be based on Planck's constant. This change would tie the definition of the kilogram to that of the second and the meter. Even though this would change the definition of the kilogram, the actual size of the unit will remain the same. The proposed changes are intended to improve the definitions of SI base units, not to actually change how the units are used throughout the world.

Ounce to Kilogram Conversion Table

Ounce [oz]Kilogram [kg]
0.01 oz0.0002834952 kg
0.1 oz0.0028349523 kg
1 oz0.0283495231 kg
2 oz0.0566990463 kg
3 oz0.0850485694 kg
5 oz0.1417476156 kg
10 oz0.2834952313 kg
20 oz0.5669904625 kg
50 oz1.4174761563 kg
100 oz2.8349523125 kg
1000 oz28.349523125 kg

How to Convert Ounce to Kilogram

1 oz = 0.0283495231 kg
1 kg = 35.2739619496 oz

Example: convert 15 oz to kg:
15 oz = 15 × 0.0283495231 kg = 0.4252428469 kg

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