How to calculate bulk density of tablets

Every one of you is familiar with the term bulk density & is also aware that we check the bulk density of powders or granules to check the flow ability and  to calculate the capacity of the rapid mixing granulators or other blenders like bin blender or double cone blender.

In this article we will learn why we calculate bulk density of the tablets & how we can calculate bulk density of the tablets.

Tablet Bulk Density

Why To Calculate Tablet Bulk Density

Tablets have nothing to do with the flow properties as in case of  powder or granules & in the same way there is no role of tablet bulk density for the blender capacity calculation.

So one of the main important questions which comes to our mind is why we have to calculate the bulk density of tablets.

The answer to the above question is that we have to calculate the bulk density of tablets to calculate the capacity of coating pans.

We are familiar that many tablets are coated after the compression process & we calculate tablet bulk density to measure how much quantity of compressed tablets can be coated in a tablet coating pan.

How To Calculate Tablet Bulk Density 

The bulk density of tablets depends on the weight,shape & dimensions of the tablets.The small weight round tablets density will be more as compared to the large weight oblong tablets. The reason is that small weight round shape tablets are closely packed & most of the void spaces are filled as compared to the oblong shaped tablets.

Following formula is used to calculate the bulk density of tablets 

                   d = m/v

d = density 

m = mass

v = volume 


Take a calibrated measuring cylinder & add a weight quantity of round shape tablets in it & note down the volume occupied. 

Suppose we add 50 grams of tablets in 100 ml of measuring cylinder & volume occupied is 60 ml.

Calculate the bulk density of tablets by putting values in above formula

         d = 50/60 = 0.833 g/ml

Now take oblong shaped tablets and repeat the same procedure as mentioned above.

Suppose 50 gm tablets occupy 80 ml & bulk density will be

       d= 50/80 = 0.625 g/ml


For more accurate results can take a 5 liter measuring jar to calculate the bulk density. 


More bulk density means more tablet weight can be added in a coating pan & less density means less amount of tablets can be added in the coating pan of same capacity.

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