When learning Japanese, one very useful grammar point is 〜か and 〜かどうか. These patterns are used to express “whether” or “whether or not”, similar to how we talk about uncertainty or indirect questions in English.

In this post, we’ll look at what they mean, how to form them, and when to use each one.

1. What do 〜か and 〜かどうか mean?

• 〜か → whether / which / if
• 〜かどうか → whether or not

They are often used when:

• You don’t know something
• You are wondering about something
• You are talking about an indirect question

Unlike English, Japanese does not change word order for indirect questions. Instead, か is added to mark uncertainty.

2. Using 〜か (Indirect Questions)

You can attach か to a question sentence and embed it inside a larger sentence.

Structure

Question sentence + か

Examples

• 私わたしは彼かれが来くるか知しりません。I don’t know whether he will come.
• どこに行いくか決きめていません。I haven’t decided where to go.
• 何なにを食たべるか考かんがえています。I’m thinking about what to eat.

👉 Here, か turns a direct question into an embedded (indirect) question.

3. Using 〜かどうか (Whether or Not)

Use 〜かどうか when there are only two possibilities:

• yes or no
• do or don’t
• will or won’t

It clearly expresses “whether or not”.

Structure

Plain form + かどうか

Examples

• 明日雨あしたあめが降ふるかどうか分わかりません。I don’t know whether it will rain tomorrow or not.
• 彼かれが本当ほんとうのことを言いっているかどうか知しりたいです。I want to know whether he is telling the truth or not.
• その映画えいがが面白おもしろいかどうか教おしえてください。Please tell me whether that movie is interesting or not.

4. 〜か vs 〜かどうか: What’s the difference?

5. Spoken Japanese Tip: 〜か Is Often Used Instead of 〜かどうか

In natural, everyday Japanese, many people often use 〜か instead of 〜かどうか, even for yes / no “whether or not” situations.

Why?

• 〜かどうか is more explicit and clear
• 〜か is shorter and sounds more natural in conversation
• In speech, Japanese speakers often drop extra words when the meaning is obvious from context

Common in conversation

• 行いくか分わからない。(I don’t know whether I’ll go or not.)
• 雨あめが降ふるか分わかる？(Do you know if it’ll rain?)

In textbooks or formal writing, you’ll often see 〜かどうか, but in casual speech, 〜か is very common and perfectly natural.

Easy rule to remember

Writing / formal situations → 〜かどうか is safer

Speaking → 〜か is often enough

6. Common Verbs Used with 〜か / 〜かどうか

These grammar patterns are frequently used with verbs like:

• 知しる (to know)
• 分わかる (to understand)
• 決きめる (to decide)
• 考かんがえる (to think)
• 聞きく (to ask)

Example

• 行いけるかどうか友ともだちに聞ききました。I asked my friend whether she can go or not.

7. Summary

• 〜か is used for indirect questions and general uncertainty
• 〜かどうか is used for clear yes/no situations
• In real conversation, native speakers often use 〜か instead of 〜かどうか
• Understanding both helps you sound more natural and confident in Japanese

Mastering these expressions will help you talk about doubts, decisions, and unknown information more smoothly in everyday Japanese.

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