how long is a piece of string?(in answer to question beginning "how long")


Senior Member
Persian - 𐎱𐎾𐎿𐎡
Hello there,
The following screenshot has been from the book English Idioms in Use Intermediate. It states that the idiom "how long is a piece of string" is utilized in answer to questions beginning with "how long ... ?". Is that true based on your experience with the English language?

  • Shandol

    Senior Member
    Persian - 𐎱𐎾𐎿𐎡
    It is being used humorously, but the idiom is well-established as far as dictionaries can tell! I'd reckon it could be humorous in a certain context, but that would come from the context, not the idiom.

    used to indicate that something cannot be given a finite measurement.

    When people say How long is a piece of string? they mean that they are not able to guess the length, size or amount of something.
    Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
    Last edited:

    Uncle Jack

    Senior Member
    British English
    It sounds perfectly ordinary to me. "How long is a piece of string?" means that whatever it is could be any length, size, duration or whatever is being talked about. Perhaps the speaker means that they don't have enough information to answer, or perhaps they mean that the question cannot be answered, not with any degree of accuracy at any rate. It is not humorous, as such (although it could be used humorously), nor do I regard it as a joke.

    In the original example, the change from "how long" referring to time to "how long" referring to length is entirely coincidental. The original question might not involve "how long" at all.


    Senior Member
    English (UK then US)
    I grew up with it in my family and at school (in England in the 50s and 60s), with the same sense as Uncle Jack describes. If it started out with some humorous intent, that had already long since faded into a set expression used to tell someone the question they are asking cannot easily be answered.


    Senior Member
    English - US
    There are about 25 other posts on the WordReference forums that mention it. I'm quite familiar with it. I think I've used it in the last two weeks.


    Senior Member
    English - U.S.
    It's the same sort of idea, but the opposite meaning, of phrases like "Does the Pope wear a funny hat?"

    Giving an example where the answer to the question makes the answer to the original obvious.


    Senior Member
    US English
    In English, we talk about "length" of a period of time. Here "length" means "duration".
    In English, we also use "length" as a physical dimension. Here "length" does not mean "duration".
    Other languages might not use the same words for these different meanings.

    For the last 700+ years there have been countless jokes mixing up the two meanings.
    This mixing does not use an idiom (at least in AE).
    This mixing does not use "string" as a standard object.

    in answer to questions beginning with "how long ... ?"
    This comment obscures the difference between "physical length" and "time duration". But I don't think any English speakers obscure that difference in their minds. We don't ask "how long" and expect an answer that could be either hours or meters.