How to Say “I Don’t Know” in English Without Losing Credibility

In a meeting, on a client call, or in a job interview, someone asks you a question, and your mind searches for the answer, but it isn't there. So you guess, give a long unclear answer, or apologise again and again. This is very common, and knowing how to say "I don't know" well is a professional skill, not a sign of weak English.

Why saying "I don't know" feels so risky

Wanting to give a complete answer comes from a good place. But under pressure, three things often get in the way.

Worrying that you'll look unprepared

In a second language, many people already feel they have to prove themselves. Not knowing an answer can feel like proof that you are not good enough.

Guessing feels safer, but isn't

A guess feels better in the moment, but a wrong guess can cause bigger problems later and damage trust.

Too many apologies

Saying "sorry" again and again can make a small gap look like a big problem. If you are not sure what the question means, it is often better to ask, as we explain in How to Ask for Clarification and Sound More Competent.

Signs this is happening to you

You might recognise some of these:

• You give long answers when you are not sure. You keep talking, hoping the answer will appear along the way.
• You say "yes" to avoid looking unprepared. It feels easier than admitting you need to check.
• You later have to correct something you said. A quick answer in the meeting becomes a difficult email the next day.

The problem is not your English. It is the pressure to always have an answer.

A real story: the developer who guessed

Steve once coached a backend developer who was on a client call. The client asked whether the system could support a new feature. He was not sure, but felt "I don't know" would look unprofessional, so he gave a long, uncertain answer that sounded like "yes". The feature later turned out to need much more work than expected, and his manager had to go back to the client to correct the answer.

Steve saw that the developer believed a professional should always have an answer. So he guessed, and the guess cost more trust than "I don't know" would have.

They practised a simple formula: say clearly that you don't know, share what you do know, and say what you will do and when, calmly and without long apologies.

Later, the client asked how long a data migration would take. He said he didn't want to give a wrong number, would check with the team, and would send an estimate the next day. He did, and his manager said this was exactly the right way to handle it.

Steve, AptSpeak's coach, puts it this way:

"Many of my clients believe that saying 'I don't know' makes them look weak, so they guess. But a wrong guess costs much more trust than an honest 'I'll find out'. Professionals aren't people who know everything. They're people who know what to do when they don't."

How to say "I don't know" professionally

Here is a simple formula you can use in any situation: I don't know + What I do know + What I'll do and when.

1. Say it clearly and calmly

Keep it short, and apologise once at most. A calm tone shows that a missing answer is normal.

• "I'm not sure about that."
• "I don't have that information right now."

2. Share what you do know

This shows that you understand the topic, even if you do not have the full answer.

• "What I can tell you is that the current version supports up to 500 users."

3. Say what you'll do and when

To get back to someone means to reply later with the answer. Always add a clear time.

• "Let me check with the team and get back to you by Friday."

4. Follow up when you said you would

Keeping your promise is what turns "I don't know" into trust. If the answer takes longer, send a short update before the deadline. For useful follow-up phrases, see What Does "Circle Back" Mean? And Other Phrases for Follow-Ups.

One important rule: never guess when the question is about numbers, dates, deadlines, or costs.

Useful phrases for three situations

These professional English phrases are short and calm. Choose the ones that feel natural.

In meetings

• "Good question. I'll find out and share it in the chat after the meeting."
• "I'd like to check that before I answer. Can I come back to you this afternoon?"

On client calls

• "I don't want to give you the wrong number. Let me confirm and send it to you tomorrow."
• "That's a great question for our technical team. I'll get back to you with an answer by Thursday."

In job interviews

If you are wondering what to say when you don't know the answer in an interview, try these:

• "I haven't worked with that tool directly, but I've used a similar one, and here's how I'd approach it…"
• "I'm not sure of the exact answer, but I'd start by checking…"

In technical interviews, showing how you would find the answer is often as important as the answer itself. If you tend to lose the question under pressure, see Why You Lose the Question in English Interviews (and How to Stop Translating in Your Head).

FAQ: how to say "I don't know" at work

Is it OK to say "I don't know" in a job interview?

Yes, if you follow it with what you do know and how you would find the answer. You can also share a real example of learning something new, using The STAR Method Explained, With Examples for Non-Native Speakers.

What if it's something I should already know?

Be honest, say you will check, and give a clear time. Then make sure you learn it, so the same question is easy next time.

How do I follow up after saying "I'll get back to you"?

Send a short message before the deadline with the answer, or with an update if you need more time. For example: "Following up on your question from yesterday's call…"

Practise tough questions with an AptSpeak coach

AptSpeak offers communication training for international professionals and for corporate teams. Our coach, Steve, is an interview and communication coach from Arizona, USA, with 13 years of experience teaching and mentoring professionals.

Steve helps you practise difficult questions in meetings, client calls, and job interviews, so you can stay calm and answer with confidence, even when you don't know the answer. His focus is building confidence, not just grammar, with clear, constructive feedback. You can start with a trial session.