Avamar Sizing tool question

Hello,

I am using the avamar ROI sizing tool on the following website: https://roianalyst.alinean.com/emc/Welcome.do

In have 130TB of VM File System Data amd 20TB of VM Database data

When I use the Gen4 7.8TB nodes the sizing tools tells me that I need 33 Storage nodes.

I uses the Avamar Data Store in a RAIN configuration.

The sizing tool say it uses 70% Deduplication of the initial backup for the File System Data and 35% for the Database data.

How does it come to 33 Nodes ?

I was expecting much less.

Please can somebody explain how this works

Regards

Ron