What and how describes the density of a magnet?

Density is a measure of the mass of a material per unit volume. All materials have different densities and the density of a magnet allows you to calculate its weight. The density values for the different magnet materials are as follows:

• Neodymium magnets have a density of up to 7.5 g per cm3.
• The density of Alnico magnets varies between 6.9 and 7.3 g per cm3 depending on the grade.
• The density of samarium-cobalt magnets varies between 8.2 and 8.4 g per cm3 depending on the grade.
• Ferrite magnets have a density of 5g per cm3
• Flexible magnets have a density of 3.5g per cm3.