The mass in kilograms of a cubic meter of anything varies widely. Any substance has a set of physical properties; properties such as melting and boiling points, appearance, solubility in different solvents, and density. Density is a measure of the mass of a specified volume of the substance, usually compared to the mass of an equal volume of water. The greater the density of the substance, the more a cubic meter will weigh.
Find the density of the substance in question from online sources or a reference book. To find online sources, search on the name of the substance and the word "density." For example, the density of gold is 19.32 g/cm³ and that of lithium is 0.53 g/cm³.
Calculate the number of cubic centimeters (cm³) in a cubic meter (m³): a cubic meter is 100 x 100 x 100 centimeters, or 1,000,000 cubic centimeters.
Calculate the mass of a cubic meter of the substance in question: multiply its density in g/cm³ times 1 million. For example, a cubic meter of gold weighs 19.32 million grams; a cubic meter of lithium weighs 530,000 grams.
Convert grams to kilograms: divide by 1,000. The mass of a cubic meter of gold is 19,320 kg (more than 21 tons); the mass of a cubic meter of lithium is 530 kg (less than 1,200 pounds).