Abap Report memory results before and after cleanup

We now have system sap on ECC6 EHP6 on database Db2 and want to migrate to S/4Hana. So,in order to get memory sizing needed for S/4hana we ran sizing abap report as in the below sap note

https://launchpad.support.sap.com/#/notes/1872170

and it get output needed memory before cleanup 3,232.6 GB and memory needed after cleanup 2,274.8 GB

So, my question is during the migration do we actually need all the memory before clean up or we can get hardware of only 2,274 GB??