How many percentage of Swelling Factor is calculated for Excavation & Back fillings?

Usually It depends upon the soil type. Your soil investigation report should assist you in this.

say for example of common earth,

Bank soil (un excavated soil) =1661 kg / cum

Loose soil (in transit after excavation) =1163 kg / cum

Compacted soil (same soil after transit) =2077 kg / cum.

therefore,

Shrinkage factor =1661 /2077 ==0.8

Load factor =1163 /1661 ==0.7

Shrinkage = {1- (1661/2077)} x100 ==20%

Swell = {(1661/1163) -1} x100 ==42%.

Hope this helps.