IDPA DP 4400- AVAMAR

We are using IDPA DP 4400.The Total capacity is 8TB, usable capacity Approx.= 7.391 TB. So, what is the compression Ratio calculation  ?

I have , 17 VM Clients .vmdk files [300,300,200,150,200,100,500,279.37,300,250,250,300,549,150,465.76,499.71,100]

             7 DB Files Backup [262.84,3.49,2.05,102.38,505.61,6.45,93.21]

             7 File System Backup [0.0677,1.72,0.07411,0.02379,1.09,0.07799,2190]

(Note: all the HDDs in GB)

Backup policy: daily 

Retention Policy: 3 days [the last 2190 GB data's Retention Policy is for 15 days]

problem : The disk is showing full.

Can someone tell me, what is the total capacity should we need in physical storage. ? [HPE Pre-sales TEAM]