The kilogram (kg) is the base unit of mass in the International System of Units (SI). It is defined as the mass of the International Prototype of the Kilogram (IPK), a platinum-iridium cylinder kept at the International Bureau of Weights and Measures (BIPM) in France.
Until May 20, 2019, the kilogram was defined by the physical prototype, but as part of the redefinition of the SI units, the kilogram was redefined in terms of fundamental constants. Since that date, the kilogram is defined by fixing the numerical value of the Planck constant (h) to be exactly 6.62607015 x 10^-34 joule-seconds.
This redefinition ensures that the value of the kilogram is now based on a constant of nature rather than relying on a physical object that could potentially change over time. It allows for a more precise and stable definition of the kilogram and other SI units.
The gram (g) is a unit of mass in the International System of Units (SI). It is one-thousandth of a kilogram, making it a smaller unit of mass.
To be more precise, one gram is equal to 0.001 kilograms, or 1 gram = 0.001 kg.
The gram is commonly used for measuring smaller masses, such as the weight of food items, small objects, or quantities of substances in scientific experiments or in everyday life. It provides a more convenient and manageable unit for expressing masses that are not as large as those typically measured in kilograms.