You're not familiar with the
1 Page = 1 Minute rule?
That is for Screenplay/Script -> Screen-time.
http://johnaugust.com/2006/how-accur...er-minute-rule
And the heuristic can be googled, where you will see that there is a LOT of discussion on the issue, but that it remains a
Heuristic (general rule-of-thumb).
And for working from Novel -> Screenplay/Script, usually you translate roughly 3 - 5 pages to 1 page of Screenplay/Script.
This is because most Novels run between 300 - 500 pages, and you want to wind up with a Screenplay that is roughly 100 - 120 Pages, to get a roughly two hour movie.
But some Novels, or especially Comic, are shorter, and you can go on a 1:1 basis. One of my friends wrote the Screenplay for the movie
The Crow, and that is the formula is basically described in creating the Screenplay, and the alterations he made from the basic Comic, since they had to provide an additional 60 pages of material. I have other friends who work in Production and Direction (most in video games - I went to High School with the owner and Founders of Ensemble Studios). And I've worked on the Talent side of Movie making for some time - I am in every Robocop movie, usually doing Stunt or Firearms work, but in two normal scenes as either extra (my first appearance in the first movie) or as Bit-Part work... And I've been in more TV than I can keep track of.
One of these friends and I have a project planned for his Graduate School work on a documentary on the depiction of Tolkien's work in Popular Media (the various movies, influence in comics and games, etc.), as well as how these seem to relate to Tolkien's own conceptions of his work.
In the course of doing that... We looked at what it would take to get The Hobbit Produced, and what a Screenplay would likely look like.*
As a Single movie, cutting down about ⅓ of the content of the book (which is roughly 300 pages - the annotated version is 305 pages for the body of the story. The Non-Annotated version is significantly longer being on smaller page sizes than the A4 on which the annotated version is printed), you can get a normal 2 hour movie, but it is going to greatly abridge a lot of stuff.
But... Looking at it as a Trilogy, you can go with a 1:1 transcription of the Book -> Screenplay to get a product that gives you 5 - 6 hours of Screen-time.
Which breaks down into 20 minutes a chapter, on average.
Which is really all that needs to be addressed, regardless of any heuristics used in the Film Industry regarding page count.
20 minutes a chapter isn't a lot of time to cover the events of a chapter, which tends to run between 15 and 40 pages each in
The Hobbit.
MB
* in the course of doing this we decided that "Movies" was a bad way to go about producing Tolkien's works, and that it would be better produced as a Cable-TV series, where each episode is 55 minutes long. We found that we can squeeze just the main Canon into four - five "seasons," with each "Season" containing 13 - 18 episodes. Or we could do a greatly expanded mythology that includes everything we can make fit into ten seasons of roughly the same length each. The one thing we wanted to add, which Tolkien never wrote anything explicitly about was the First War between the Elves and Sauron in the
Second Age. Considering that all we would have to do would be to avoid including anything or anyone that would contradict the established Canon, we thought it was do-able, even if fraught.