This phrase "I will not fail you", Is it formal or informal?

What are the other words used to convey the same feelings?

  • 2
    I'm not sure what you mean by "formal" and "informal" in this context. Perhaps you should elaborate on that.
    – J.R.
    Mar 12, 2013 at 7:31
  • I mean, where is it suited perfect, in official way(formal) or in friendly manner(informal)? Mar 12, 2013 at 7:43
  • 4
    A great portion of the English language can be used in both formal (official) and informal (friendly) contexts. I would regard the sentence "I will not fail you" to be among those utterances that would fit just fine into either setting; I wouldn't regard it as overly stilted in a friendly conversation, nor as too colloquial for a formal speech.
    – J.R.
    Mar 12, 2013 at 7:49
  • 2
    I think you might enjoy ELL even more, if you haven't been there yet. That site is specifically for people who are learning the English language, and for questions that would be pretty obvious for most native speakers. Had you asked this question there, instead of here, I would have left an answer instead of a comment.
    – J.R.
    Mar 12, 2013 at 8:48
  • 3
    The above comments make sense. I think the formal / informal classification is perhaps the wrong one to consider here; the serious / light classification makes sense. 'I will not fail you' certainly isn't light banter, and sounds more serious (yes, and admittedly more formal) than 'I won't let you down'. Mar 12, 2013 at 9:36

2 Answers 2


I would say it's informal since to fail is regularly used like to fail at something. Other ways to say this would be:

I will not disappoint you

I will rise to your expectations


Yes, the phrase is formal. This phrase has similar meaning:

I won't let you down


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