Translation guide
How to say 'I don't know' in Japanese, covering lack of knowledge, uncertainty, and polite refusals.
Expressing that you do not know a fact, answer, or piece of information.
Polite and standard way to say 'I don't know.' Suitable for most situations.
すみません、答えを知りません。
Sorry, I don't know the answer.
Polite and common. Implies 'I don't understand' or 'I'm not sure,' often used when you can't figure something out.
この問題が分かりません。
I don't understand this problem.
Casual form of 'I don't know.' Used with friends and family. Can sound blunt if used in polite contexts.
あの人の名前、知らない。
I don't know that person's name.
Casual form of 'I don't understand/know.' Very common in informal speech.
何を言ってるか分からない。
I don't know what you're saying.
Humble form of 'I don't know.' Used in very formal or business settings to show respect.
その件については存じません。
I am not aware of that matter.
Expressing that you are not sure about something, or that you cannot decide.
Also used for uncertainty. Often softened with ちょっと (a little).
ちょっと分かりません。
I'm not really sure.
Attached to verb stems to mean 'cannot possibly do.' Formal and indirect way to say you don't know or can't do something.
お答えしかねます。
I'm afraid I cannot answer that.
Pattern meaning 'I don't know whether or not...'
彼が来るかどうか分からない。
I don't know whether he will come or not.
Using 'I don't know' to politely decline to answer or to avoid giving a direct response.
Trailing off with 'a little...' is a common way to indirectly refuse or show hesitation without saying 'I don't know' directly.
A: 明日来られる？ B: ちょっと…
A: Can you come tomorrow? B: Well, it's a bit...
Formal way to say 'I'm not in a position to know/answer.' Used in customer service.
その質問にはお答えしかねます。
I'm unable to answer that question.
知らない (shiranai) means you lack the information. 分からない (wakaranai) means you don't understand or can't figure it out. In many situations they overlap, but 分からない is more about comprehension.
彼の電話番号を知らない。
I don't know his phone number. (I never had the info.)
この漢字の読み方が分からない。
I don't know how to read this kanji. (I can't figure it out.)
Directly saying 知りません to a request can sound cold. Use softer expressions like ちょっと… or 分かりかねます to be polite.