Hausner ratio

The Hausner ratio is an indication of the compressibility of a powder. It is calculated by the formula $$H=\frac{\rho_T}{\rho_B}$$, where $$\rho_B$$ is the freely settled bulk density of the powder, and $$\rho_T$$ is the tapped density of the powder.

The Hausner ratio is frequently used in pharmaceutics as an indication of the flowability of a powder. A Hausner ratio greater than 1.25 is considered to be an indication of poor flowability.

The Hausner ratio is related to the Carr index, another indication of flowability, by the formula $$H=C/100+1$$.