How to say “I don't understand” in Japanese
How to say I don't understand in Japanese: わかりません (polite) vs わからない (casual), why 知りません can sound cold, native audio for both, and an AI grader that scores you.
わかりません。
I don't understand.
わからない。
I don't understand.
When to use which
わかりません (wakarimasen) is the polite "I don't understand"; わからない is the casual form. It may be the highest-value sentence a beginner can produce, because it keeps a conversation alive instead of ending it — said with engagement, it invites the other person to slow down or rephrase rather than give up and switch to English.
The distinction English hides: Japanese splits "I don't know" into two verbs. わかりません means you can't work it out — you heard the words but the meaning didn't land. 知りません (shirimasen) means you don't possess the information — you never had it. Notice how the second one arrives with a softener attached: すみません、知りません, or casually ごめん、知らない. That isn't decoration. Bare 知りません can read as a curt "not my problem," so the apology in front does real work. The classic learner mistake is mapping English "I don't know" onto 知りません everywhere, which comes out colder than intended; when in doubt, わかりません is the safer and warmer default.
Two useful attachments: soften with ちょっと — ちょっとわかりません, "I don't quite follow" — and follow up with もう一度お願いします ("once more, please") to turn the admission into a request. Not understanding, said fluently, is its own kind of fluency.
Now say it yourself
Type or speak your Japanese below — the AI grades your grammar, vocabulary, and register on the spot.
Answer in Japanese — an AI character grades it, then roasts it in their own voice. Pick your character:
わかりません keeps a conversation alive; 知りません, said bare, can end one — English folds both into "I don't know," which is exactly why learners get it wrong.
Frequently asked
What's the difference between わかりません and 知りません?
わかりません means you can't understand or work something out; 知りません means you don't have the information at all. For a question you didn't catch, use わかりません. For facts you genuinely don't know, soften it: すみません、知りません.
Is 知らない rude?
It can be. Between friends, tone carries it — ごめん、知らない is fine. Said flat to a stranger, 知らない or 知りません sounds dismissive, like "how should I know." Leading with an apology fixes it.
How do I ask someone to repeat themselves in Japanese?
もう一度お願いします — "once more, please." Pair it with わかりません and you've turned "I'm lost" into "help me get it," which is what keeps native speakers engaged instead of switching to English.
Try JIVX free
Full N5 access, no credit card, no trial limit. 2,500+ sentences with native audio, voice input, and AI grading on everything you produce.
Start Practicing