How to say “I don't know” in Korean

"I don't know" in Korean is 모르겠어요 (moreugesseoyo), a polite and soft way to say it. With friends you can say 몰라 (molla).

Ways to say it

Korean	Level	When to use it
모르겠어요 moreugesseoyo	Polite	Polite and gentle. Sounds like "I'm not sure". The best choice for most situations.
잘 모르겠어요 jal moreugesseoyo	Polite	"I'm not really sure." Even softer and very common.
모르겠습니다 moreugesseumnida	Formal	For work, customers, or speaking to someone much older.
몰라요 mollayo	Polite	A plain "I don't know". Polite, but can sound a bit blunt depending on tone.
몰라 molla	Casual	"Dunno" to friends. Said sharply, it can sound like "I don't care".
글쎄요 geulsseyo	Polite	"Well..." or "Hmm, I'm not sure" when you need time to think.

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A tourist asks you for directions

Sorry, I'm not sure.

A friend asks what you want to eat

I don't know, anything.

Your boss asks about a schedule

I don't know yet.

모르겠어요 sounds softer than 몰라요 because the -겠- part makes it feel like "I can't say" rather than a flat "I don't know".

몰라 is very common between friends, but in an argument it can sound dismissive, like "whatever".

The base verb is 모르다 (to not know). Korean has a separate verb for not knowing, so you do not need a word for "not".

More on 모르겠어요 and 몰라 in our Korean phrase guides.

What is the difference between molla and moreugesseoyo?

몰라 (molla) is casual and short. 모르겠어요 (moreugesseoyo) is polite and softer, so use it with anyone you are not close to.

How do you say "I'm not sure" in Korean?

Say 잘 모르겠어요 (jal moreugesseoyo). It is polite and very natural.