These days, scripts aimed at the Hollywood system are typically 110 pages, more or less. 120's okay. More than 130's a real problem.
According to various pro readers, the story should change around page 30, page 60, and page 90. So the ending runs about 20 pages or so. By "ending" I mean the inexorable, inevitable movement towards the conclusion.
But this is story craft. The length of the ending should be appropriate to the story. It's not something you can figure out by taking a general poll.
Best advice I can give is find ten movies in the same genre as the one you're writing, and figure out why their endings work the way they do. Figure out what works for you, and what doesn't. Apply what you've learned to your own script.
Be prepared to take your carefully worked out intros and endings and just throw them away (metaphorically speaking, that is.) If your story can work without the lovingly crafted finish, you're better off leaving it out.
Think outside the box. Take the middle and make it the end. Take the end, and make it the beginning. Take the beginning, and bury it your backyard.
