"Three or four years would be accurate, I would say," Jackson said.
The rights to J R R Tolkien's novel, The Hobbit, are split between two major Hollywood studios, MGM and New Line Cinema.
Jackson said he was keen to return to Middle Earth for The Hobbit but that MGM's sale to Sony Corporation made the project's future unclear.
"I think there is probably a will and a desire to try and get it made," he said.
"But I think it's gonna be a lot of lawyers sitting in a room trying to thrash out a deal before it will ever happen."