18 Other Ways to Say “I Don’t Know”

None of us has all the answers. That’s why you might say “I don’t know” from time to time. But is this always an appropriate response?

We’ve compiled a list of useful synonyms for this phrase that you can use in formal and informal settings. So, even though you may not have an answer, you’ll always have a good response!

Other Ways to Say “I Don’t Know”

  • I’ll look into that
  • No clue
  • I’m not sure
  • I haven’t the foggiest
  • I have no idea
  • Your guess is as good as mine
  • I’m unsure
  • Beats me
  • Good question
  • I’ll get back to you on that
  • Lord knows
  • Don’t ask me
  • I haven’t an inkling
  • I can find that out
  • I’ve been wondering the same thing
  • It’s beyond me
  • It’s a mystery to me
  • Let me look that up for you


  • The phrase “I don’t know” is an acceptable answer in both formal and informal settings, but whether or not it is proper to use depends on context.
  • As an informal alternative to this phrase, you can say “no clue.”
  • In formal settings, it would be better to say “I’ll look into that.”

Keep reading to see how we use our choice of formal and informal synonyms for “I don’t know” in a couple of helpful examples.

After that, we’ll discuss when it would be appropriate to say “I don’t know” in response to a question.

I’ll Look Into That (Formal)

If you’re wondering how to say “I don’t know” professionally, we would suggest simply saying “I’ll look into that” instead.

This phrase makes it clear that you don’t have an answer on hand. However, it makes you appear competent and proactive. After all, it’s good for your boss or coworker to know that you will find the answer promptly.

This phrase is a better one to use in formal circumstances than “I don’t know.” After all, it’s okay not to know everything. But you should show that you are capable of finding things out, especially in the workplace.

To see this phrase in action, let’s look at a formal email example:

Dear Zarah,

I’ll look into that question you had regarding the tax department’s income source detection process and get back to you within the hour.


Finally, let’s see a dialogue example making use of this phrase:

Person 1: Does that legislation apply to this county?

Person 2: I’ll look into that and let you know.

No Clue (Informal)

If you’re seeking out what to say instead of “I don’t know” in informal settings, our top pick is the phrase “no clue.”

This phrase isn’t a better one than “I don’t know” per se. In fact, they can be used interchangeably. However, you can use this phrase to avoid repetition in your daily conversations. After all, saying “I don’t know” all the time might get dull.

We wouldn’t recommend using this phrase in response to your employer or a person of superior rank to you at work. However, you can use it when speaking casually to your coworkers or outside of the office.

Consider the examples below to see what we mean:

Person 1: Is Mr. Hargrove going to make his appointment?

Person 2: No clue; we can’t get hold of him.

I’m afraid I have no clue what time the building usually shuts down. Let me contact the front desk and see if they can help.

Is “I Don’t Know” an Acceptable Answer?

It’s okay to say “I don’t know” in formal and informal contexts. However, whether the phrase “I don’t know” is an acceptable answer depends on context.

On one hand, if you don’t know the answer to a question, it’s best to be honest about that. You should never pretend to know something you don’t.

Moreover, sometimes a topic of discussion is very complicated. Therefore, there may be no objectively correct response. In that instance, “I don’t know” is a proper answer and a way to respond politely.

However, this answer may not be enough in a professional scenario. If you are asked a question by your boss or a client, responding with “I don’t know” and nothing further won’t come across as very impressive or professional.

In such an instance, you would be better off using one of our formal synonyms as a response. Namely, you should say that you don’t know the answer, but you will find it out for them.

You can also use our list of synonyms to find an informal alternative if you think the original phrase is a tad worn out.

In conclusion, it’s okay to say “I don’t know,” especially if you’re asked a complicated question with no one true answer. However, if you’re wondering how to say “I don’t know” in a smart way, one of our formal synonyms should help.

If you think our list of synonyms is useful, why not bookmark this page to keep them on hand?