I have a SQL 2014 SP3 instance, one database is over 2TB, I ran 

```
DBCC CHECKDB WITH ESTIMATEONLY
```

Results are 

> DBCC results for 'BIGdb'.
Estimated TEMPDB space (in KB) needed for CHECKDB on database > DBCC results for 'BIGdb' = 679801144.
DBCC execution completed. If DBCC printed error messages, contact your system administrator.

>Completion time: 2020-05-05T06:40:43.4776438-04:00

That is almost 700GB.

The tempdb on this server is only 60GB and the intregrity check runs every weekend.  

I find a number of posts like this one by Paul https://www.sqlskills.com/blogs/paul/how-does-dbcc-checkdb-with-estimateonly-work/ suggesting the result may be low.

I don't find anything talking about the results being significantly higher (over estimated) 

What could or does cause the estimate to by **Very** high? 

Clearly I don't want to add 700GB+ of disk space when less then 100 will do.  Short of trying how can I know that the estimate is very high?

P.S. I am not worried about this system, but I am getting a very high estimate on a different server.  I need to know if that is very highly wrong, before adding space.