Peter Jackson has received a fair amount of criticism for stretching the 333 page The Hobbit into a trilogy of three hour movies. Which got Centives wondering: how long are other movies compared to the books they’re based on? And how does the amount of time spent per page affect the rating of the movie?

We took a look at books that have been turned into major movies over the past six years. We then took its runtime in minutes and divided it by the number of pages that Amazon lists for the paperback version of the book to figure out how many minutes of film there are for each page of the book*. This is how that compares to its “tomatometer” score on Rotten Tomatoes:

Overall there was a positive correlation of 0.25 which indicates that the more time spent per page of book, the better the critics rated it. Perhaps this is because it gives the filmmaker more time to do justice to a book which, if movie studios are willing to invest millions to convert into a movie, is likely a good book.

The films that scored at least 90% on Rotten Tomatoes spent, on average, 0.4 minutes of screen time for every page of the book. Examples include The Social Network, Moneyball, Slumdog Millionaire, and Harry Potter and the Deathly Hallows Part II. The films that scored 20% or less only had 0.2 minutes of film for every page of the book.

Peter Jackson’s Hobbit films are clearly outliers, spending over a minute and a half of film for every page of the book – three times the amount for the Lord of the Rings trilogy which, on average, spent just 30 seconds per page – but they’re far from bad movies. The two so far have an average score of 70%. The other films based on books in our sample have an average score of 57%. Let’s just hope Peter Jackson doesn’t find out about the 12 volume The History of Middle Earth. At three movies a book he’d be busy making films in Middle Earth through 2050.

Now find out how many dragons a medieval country could support.

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*In cases such as The Hobbit and Harry Potter and the Deathly Hallows where multiple movies covered one book we divided the book’s number of pages by the number of movies (thus each of the three Hobbit movies is assumed to cover 111 of the book’s 333 pages).