What does 'happen to do' mean? For example,

I happen to know that.
Did you happen to let him know?
How did you happen to hear that?

I really want to know the difference between "I know that." and "I happen to know that."

I was taught there exists some difference between them but usually failed to understand what it means.

  • 2
    happen to means By chance. I happen to know that=by chance, I know that.
    – Lambie
    Aug 16, 2016 at 17:43
  • 1
    I've always thought of it as a way of saying, "It's by chance that I know that", as @Lambie offered, but also another way of saying "by pure coincidence I have that (thing, knowledge, information)" or "by sheer luck, I have what you need" as some examples. Aug 16, 2016 at 18:01
  • Yeah I have taught like that. I mean it meat 'by chance'. But when I watch so many American soaps then I feel many sayings seem not to mean 'by chance'...so that is why I am always confused. Thank you for your comments!!!
    – Diana Jang
    Aug 17, 2016 at 13:03
  • More links: google.com/search?q=%22i+happened+to%22
    – Pacerier
    May 10, 2017 at 14:16

3 Answers 3


The phrase happen to appears to be used in the following ways usually. When you're asking someone 'Do you happen to know this person or information?', it indicates that you believe chances are that they don't know that person or information but you're exploring the remote possibility that they might.

Similarly when you're saying that you happen to know someone or some piece of information when not initially asked if you happen to know, you'd be doing it to convey that it was unexpected, but you do know.

This might help clear some aspects of the usage for you: http://www.phrasemix.com/phrases/happen-to-do-something


Consider this conversation: A: "I wonder where he was born?" B: "It just so happens I know that."

Person B could have said "What a remarkable coincidence! I know the answer to the question you just asked!" In this case, the word happens indicates a coincidence; just and so are extra words that really add very little to person B's statement.

  • Thank you for your answer. But I have a question. Is that the same situation that I asked? I was questioning about this kind of example like 'happen to + infinitive'
    – Diana Jang
    Aug 17, 2016 at 13:10

Happen to is quite likely saying by any / some mean(s).

Your examples may be recast as follows.

By some means, I know that.

Did you, by any means, let him know?

  • ...him know? I'm not familiar with that construction. I'm also not sure about the passive voice. Isn't "I happen to have that information" considered 1st person voice? Aug 16, 2016 at 18:03
  • In your last example: "How did you happen to hear that?"; "happen" and "to" aren't linked, as we can rewrite like: "How it has happened you heard that?"
    – Luke
    Aug 16, 2016 at 18:04
  • As I know the expression, "happen" and "to" are linked. You can exclude the phrase to say "How did you (happen to) hear about us?" How would you use "by some/any means" in its place? Aug 16, 2016 at 18:07
  • What do you mean, "it is always in the passive voice"? I know that is not passive, even if you add "by some means". Aug 16, 2016 at 18:22
  • @Mr.ShinyandNew安宇 You're right, I messed things up. Thanks for the advice.
    – Luke
    Aug 16, 2016 at 18:28

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