hausner ratio hausner ratio the hausner ratio is a number that is correlated to the flowability of a powder or granular material. it is named after the engineer henry h. hausner (1900–1995). the hausner ratio is calculated by the formula h = ρ t ρ b where ρ b is the freely settled bulk density of the powder, and ρ t is the tapped bulk density of the powder. the hausner ratio is not an absolute property of a material; its value can vary depending on the methodology used to determine it. the hausner ratio is used in a wide variety of industries as an indication of the flowability of a powder. a hausner ratio greater than 1.25 - 1.4 is considered to be an indication of poor flowability. the hausner ratio (h) is related to the carr index (c), another indication of flowability, by the formula h = 100 / ( 100 − c ) . both the hausner ratio and the carr index are sometimes criticized, despite their relationships to flowability being established empirically, as not having a strong theoretical basis. use of these measures persists, however, because the equipment required to perform the analysis is relatively cheap and the technique is easy to learn.