You do know that you do not need to post
the same question in both the calibre and Sigil forums at the same time?
If there wasn't an answer, we'd just tell you to use the calibre plugin.
Fortunately, there is an answer -- Reports.
That is kind of the fundamental reason for a Reports feature to exist.
And just so you can cover all your bases (because I think you forgot to post a third thread in the calibre Editor forum), the calibre Editor has a Reports feature too, which also provides this data.
It's like, no matter where you turn, you can't get away from this feature!
All you need to do is ask --
once.
... no need to chase down a tool in a separate application which removes you from your workflow...
**Doesn't want to paste into Word, so instead he imports into calibre and runs a plugin.
**