Post length limits?

What are the character limits for each of the following types of posts?

The reason I ask is that I’m going to publish a long review of the new movie on Reddit tomorrow and am thinking of reposting it in the Pony Discussion board over here (since both sites use MD now). However, it’ll be bumping right up against the 40,000 character limit for a single Reddit post. If I’d need to break it into multiple posts, then I’ll leave it as a Reddit exclusive.

@PUBLIQclopAccountant
20,000 characters for posts and comments. 50,000 for image descriptions.

@Princess Celestia
Thank you, Princess. TIL that image descriptions can have over twice the characters as forum posts and comments.

@PUBLIQclopAccountant
Also, You can only make 1000 messages in a private message line

Thanks for all these informations guys. Good to know :)