Export-SPWeb: estimate size of cmp from 40GB SPWeb

I have an SPWeb I want to export into a cmp file to import into a new site collection. I've had a 100GB volume allocated for it, but I'm getting

Export-SPWeb: There is not enough space on the disk.

Is there a way to estimate how large the cmp will be based on an SPWeb's size?

Ran http://get-spscripts.com/2010/08/check-size-of-sharepoint-2010-sites.html and got SPWeb is 40GB.

Thanks.

Scott