The filmmaker revealed that the first part of the upcoming trilogy will be his shortest movie set in Middle-earth, clocking in at around two hours, 40 minutes.
"It's looking like it's going to be about ten minutes shorter than Fellowship was," Jackson told Empire. "So it's going to be officially our shortest Middle-earth yet.
"I mean, Fellowship was just under three hours and this is about two hours, 40 minutes at the moment."
The report notes that the end credits reel is still to be added to the filmed footage and some of the effects shots are yet to be finalised, but the running time is unlikely to be significantly altered by these factors.
An Unexpected Journey will be the first of three Hobbit instalments, with Martin Freeman, Sir Ian McKellen and Andy Serkis leading an all-star cast.
The Hobbit: An Unexpected Journey will be released on December 14. Watch a trailer for the film below: