Hello Trevor,
Welcome to Communities.
I am not aware of such a resource online but the math behind calculating such things is not overly complicated:
(raw capacity x (raw capacity - slack))/FTT&FTM overhead
e.g. if you have 10TB raw, with 25% saved for slack space and using FTT=1,FTM=RAID1 then it would be:
(10 x 0.75)/2 = 3.75
Where it gets more complicated is if you have a mix of Storage Policies with different FTTs and FTMs in use (e.g. FTT=2,RAID1 uses 3x the base size while FTT=2,RAID6 uses 1.5x) and other factors such as dedupe ratio if deduplication is used.
Planning Capacity in vSAN
Bob