Calculating Disk Space for Content Revisions?

SEPM 12.1.4

I'm looking at increasing the number of content revisions held on the SEPM. We currently have it set at 7. I see the size of the Inetpub\Content folder is 22GB. Can I assume that if I doubled the setting to 14 that the file sizes will double also? I only have 30GB available on our SEPM.

Is there a method for caculating size of revisions? I've looked at the following article but it doesn't say: https://support.symantec.com/en_US/article.TECH96214.html

Thanks.