# Metric System Conversion Calculator

To use the calculator, place your cursor in the desired unit field and write a number. If needed use the dot "." as the decimal separator.

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kg
g
ct
mg
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## Did you know?

Use the overview below to better understand the meaning and history of the different weight units.

• ##### Tonne `(1,000,000 grams)`
The tonne commonly referred to as the metric ton in the United States, is a non-SI metric unit of mass equal to 1,000 kilograms or one megagram (Mg); it is equivalent to approximately 2,204.6 pounds, 1.102 short tons (US) or 0.984 long tons (imperial). Although not part of the SI, the tonne is accepted for use with SI units and prefixes by the International Committee for Weights and Measures.
• ##### Kilogram `(1,000 grams)`
The kilogram or kilogramme (symbol: kg) is the base unit of mass in the International System of Units (SI), and is defined as being equal to the mass of the International Prototype of the Kilogram a cylinder of platinum-iridium alloy stored by the International Bureau of Weights and Measures at Saint-Cloud, France.
• ##### Gram `(1 gram)`
The gram (alternative spelling: gramme; SI unit symbol: g) is a metric system unit of mass. Originally defined as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre [1 cm3], and at the temperature of melting ice" (later at 4 °C, the temperature of maximum density of water). However, in a reversal of reference and defined units, a gram is now defined as one one-thousandth of the SI base unit, the kilogram, or 1×10−3 kg, which itself is now defined, not in terms of grams, but as being equal to the mass of a physical prototype of a specific alloy kept locked up and preserved by the International Bureau of Weights and Measures.
• ##### Carat `(0.2 g)`
The carat (ct) (not to be confused with the karat, sometimes spelled carat, a unit of purity of gold alloys), is a unit of mass equal to 200 mg (0.2 g; 0.007055 oz) and is used for measuring gemstones and pearls. The current definition, sometimes known as the metric carat, was adopted in 1907 at the Fourth General Conference on Weights and Measures, and soon afterwards in many countries around the world.
• ##### Milligram `(0.001 grams)`
A unit of measurement of mass in the metric system equal to a thousandth of a gram. A gram is equal to the mass of one milliliter, one thousandth of a liter, of water at 4 degrees C. The abbreviation for milligram is mg.
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