The Correct Answer is:

I realize a many individuals trust he’s around 8’5″, yet he said he was dead. (“… and now that I’m dead, I might eliminate my cap and present Shakespearean statements”) So, he must be alive eventually, and it’s farfetched that he developed to godlike level while living. Despite the fact that he seems, by all accounts, to be very tall, I would appraise him to be around 6’5″, yet that is basically the way in which tall he showed up in the film. Nonetheless, soon after the film’s delivery, an item named a “day to day existence size cardboard pattern” of Jack Skellington with a level of 5’10” was delivered, subsequently it’s entirely conceivable that is his level.