Since there are 1,000 grams in one kilogram, 100 grams is the equivalent of 0.1 kilogram. To convert from grams to kilograms, simply divide the number of grams by 1,000.
The kilogram represents the base unit of mass in the International System of Units (SI). One kilogram is equal to the mass of one liter of water. Since there are 1,000 grams in one kilogram and 1,000 cubic centimeters in one liter, a gram is the mass of one cubic centimeter of water. The kilogram is the only SI unit that is still defined by a physical artifact, which is known as the international prototype kilogram (IPK). The original IPK and six sister copies are stored near Paris, France.