How long do you think a forum post should be? Do you have any rules? Well, on my forums, I do not have any rules for post length but in my posting guidelines I mention that the ideal length of posts and topics should be at least 40-50 words. This is just a suggestion and not a rule, though. I recommend users making 40-50 words post because I think the post needs to be of certain length to add value to the discussion.