The literature on density measurements, with a particular interest in methods suitable for liquid cast iron, is reviewed. Different measurement methods based on a number of physical properties are highlighted and compared. Methods for the calculation of density are also reviewed, and the influence of alloying elements on density is, to some extent, discussed. The topic is of essence for the understanding of the material behaviour at solidification, which is pivotal in software applications for casting simulation. Since a deeper understanding of the relationship between the density of liquid cast iron and volume expansion is necessary, the conclusion that further research within the field is needed lies close at hand.