Several sites and forum or general site engines use or at least provide the possibility of limitation in the length of posted comments, posts and/or replies. Stack Exchange engine, for example, has a quite strict limit in case of comments.

What can help determining the ideal length? Too low limit might cause mild frustration in the user.

  • 2
    I would expect it depends on what the comments are for. Take SE for example. It's enough to provide a fair amount of clarification or reasoning without running on to basically form comment-questions/answers (usually). This way, a single run-on comment cannot dominate the entire section of a post. Sure, a user could split it, but it's rarely an issue and a limit definitely discourages it. Aug 30, 2016 at 16:53
  • It's a question of context I guess. From a users point of view do they want restricting at all? Ask the question, what are you trying to achieve with a limit and see where that leads.
    – Jonny
    Aug 30, 2016 at 16:57

2 Answers 2


I have found in all of my designs the limitation on how big a comment can be is based either by the business not wanting to read long comments, or by some Tech Arch / Data Arch claiming that it will take too long to fetch or will take up too much space in the data base.

From an ideal perspective there is no reason to limit what is captured, just put in a visual break on the content around the 300 - 500 character mark with a "more..." type prompt at the end. This allows the reader to get some context and choose to read the rest while exposing more of the other information on the screen to the user.

  • I've had a nastier assumption: spambots way write very long comments, wasting a lot of space, and limitations can prevent, or at least ease this problem. Aug 30, 2016 at 21:06
  • That's a good point. Do you have a problem with spambots or are you trying to solve a potential problem? From a design point of view you could re-frame your problem to something like - "How might we prevent the nasty side effects of spambots (specify what these might be) without affecting a real users experience of making a comment". Could be an interesting UX stack exchange question...
    – Jonny
    Aug 31, 2016 at 9:30

I think length restrictions can be informed by the behaviours the site wants to encourage and/or discourage. A large character limit can encourage users to engage in discussion or to write detailed and well researched posts. While, a small character limit would set an expectation for directness and brevity in posts.

This can work well in the aggregate, but is not fool proof. StackExchange wants to ensure that comments are not used to post answers. But the 600 character restriction cannot prevent contributors from writing short answers as comments. Sometimes the limitation is just technological. Twitter's 140 character limit is a holdover from its origin as an SMS service (SMS has a 165 character limit).

I think the frustration of hitting the limit is a reminder to the user that their current expectations don't align with the sanctioned behaviours for the site. If the limitation is unusual then the site probably needs to have an explanation near at hand. Again, StackExchange does a good job of this the placeholder text for comments tells the user what should and shouldn't be there.

enter image description here

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.