The bulk density of a material is the ratio of the mass to the volume (including the inter-particle void volume) of an untapped powder sample. 

The tapped density of powders or granulates is an increased bulk density attained after mechanically tapping a cylinder containing the sample.  

Analysis of Bulk and tapped density of powder give you a possibility: 

1. To calculate the compressibility index and Hausner Ratio of your powder 
2. These parameters give you an understanding of powder flowability and compressibility 

For Material experts: 

Instrument and measuring principle 

Bulk density depends on the density of the powder particles and their arrangement and the results are influenced by the preparation, treatment and storage of the sample material. The method used for measuring the bulk and tapped density of powders is described in the European Pharmacopoeia