How to Say “I Don’t Understand” in Japanese: わかりません

The short answer

Say わかりません (wakarimasen) when you do not understand. It is polite and useful with teachers, strangers and people you do not know well.

Japanese often leaves out わたし (watashi, I) when the speaker is already clear.

Understand and not understand

わかります (wakarimasu) means “I understand.” Replace the polite ending ます with ません to make the negative form.

Do not add です after either form. The verb is already polite.

Say what you do not understand

A useful beginner pattern is [thing] + が + わかります or わかりません.

For example, use 日本語 (nihongo, Japanese) or 英語 (eigo, English) before が.

If が still feels unfamiliar, continue with the beginner guide to は and が.

Tell the other person how to help

わかりません identifies the problem. Add a short request when repetition or slower speech would help.

Use すみません (sumimasen) first to get attention politely.

A fuller request is もう少し、ゆっくり言ってください (mou sukoshi, yukkuri itte kudasai): “Please speak a little more slowly.” The shorter ゆっくり、お願いします is easier to remember and still tells the listener what you need.

Answer a question about understanding

わかりません and 知りません

English can translate both as “I don't know,” but the focus differs. 知りません (shirimasen) says that you do not possess a fact or do not know a person. わかりません says that you do not understand, cannot work something out or do not know the answer in the situation.

This is a practical distinction, not a one-word translation rule. Japanese speakers can use わかりません when they cannot give an answer to an information question.

わかりません and できません

わかりません is about understanding. できません (dekimasen) is about ability or whether something can be done.

Common beginner mistakes

• Saying わかりませんです. Use わかりません by itself; it is already polite.
• Missing the negative ending. わかります means “I understand,” while わかりません means “I don't understand.”
• Treating わかりません and 知りません as perfectly interchangeable. Choose according to whether the issue is understanding, working out an answer or possessing information.
• Stopping at わかりません when you know what would help. Ask for repetition or slower speech too.

Practise saying it

Say these lines aloud as one short repair sequence.

Then replace 日本語 in 日本語がわかりません with 英語 (English) or another language you know.

A short role-play

Quick quiz

1. How do you say “I don't understand”?
2. How do you say “I understand”?
3. How do you politely ask for one more time?
4. Which phrase focuses on not knowing a person: わかりません or 知りません?
5. What is the difference between わかりません and できません?

Answers

1. わかりません (wakarimasen).
2. わかります (wakarimasu).
3. もう一度、お願いします (mou ichido, onegaishimasu).
4. 知りません (shirimasen).
5. わかりません is about understanding; できません is about ability.

Frequently asked questions

Is わからない the same as わかりません?

They express the same basic idea, but わからない (wakaranai) is casual. Start with polite わかりません when you are unsure which level of politeness fits.

Can わかりません mean “I don't know”?

Yes. It can mean that you do not know or cannot work out the answer, as well as that you do not understand. Context decides the best English translation.

How do I ask someone to speak slowly?

Say ゆっくり、お願いします (yukkuri, onegaishimasu). For a fuller request, use もう少し、ゆっくり言ってください (mou sukoshi, yukkuri itte kudasai).

Continue learning

Build the everyday words you need with the YapaneseAI vocabulary library. If you still rely heavily on romaji, practise reading the examples with the hiragana and katakana charts.