か (Question / Or)疑問・選択
か has three major functions: turning a statement into a question, offering a choice between alternatives ("or"), and combining with question words to create indefinite words like "someone" (誰か) and "something" (何か).
か has three major functions: turning a statement into a question, offering a choice between alternatives ("or"), and combining with question words to create indefinite words like "someone" (誰か) and "something" (何か).
Use 1: Question marker
Add か to the end of a sentence to make it a question: 行きますか (Will you go?), これは何ですか (What is this?), 日本語が分かりますか (Do you understand Japanese?). In polite speech, か is always used. In casual speech, questions are often formed with rising intonation alone, without か.
Casual questions without か
In casual speech: 行く？ (Going?), これ何？ (What’s this?). Adding か in casual speech can sound blunt or rude: 行くか can sound like a rough male demand. Learners should use か in polite speech and rising intonation in casual speech.
Use 2: Or (offering alternatives)
か between options means "or": コーヒーかお茶 (coffee or tea), 行くか行かないか (whether to go or not), 土曜日か日曜日 (Saturday or Sunday). This use works both in questions and statements.
Use 3: Question word + か = someone/something/somewhere
Adding か to a question word creates an indefinite: 誰か (someone), 何か (something), どこか (somewhere), いつか (sometime). 誰か来ましたか (Did someone come?), 何か食べたい (I want to eat something). This is the positive counterpart of question word + も + negative.
Use 4: Embedded questions
か marks a question inside a larger sentence: いつ来るか分からない (I don't know when they’ll come), 何を買ったか忘れた (I forgot what I bought). The embedded question uses plain form + か. In polite speech, add どうか for yes/no embedded questions: 行くかどうか分からない (I don’t know whether they'll go or not).
Example sentences
すみません、トイレはどこですか。
Sumimasen, toire wa doko desu ka.
Excuse me, where is the restroom?
か = polite question
バスか電車で行けます。
Basu ka densha de ikemasu.
You can go by bus or train.
か = or (choice)
誰か手伝ってくれませんか。
Dareka tetsudatte kuremasen ka.
Could someone help me?
誰か = someone
明日来るかどうか教えてください。
Ashita kuru ka douka oshiete kudasai.
Please tell me whether you're coming tomorrow.
かどうか = whether or not
いつか日本に行きたい。
Itsuka Nihon ni ikitai.
I want to go to Japan someday.
いつか = sometime
Common mistakes
行くか？(to a colleague in polite context)
行きますか？
In polite situations, use the masu form + か. Plain form + か sounds blunt or masculine-rough.
何か知りませんか (meaning "I don't know anything")
何も知りません
何か = something (indefinite). 何も + negative = nothing. These are different patterns. 何か知りませんか means "Do you know something?"
いつ来ますか分からない (embedded question in polite form)
いつ来るか分からない
Embedded questions use plain form before か, even when the main clause is polite: いつ来るか分かりません.
Frequently asked questions
Is it rude to use か in casual speech?
It can be. Plain form + か (行くか？) has a blunt, sometimes rough nuance. Women and younger speakers often avoid it in casual speech, preferring rising intonation instead (行く？). In polite speech (行きますか？), か is always appropriate and expected.
What is the difference between 誰か and 誰も?
誰か = someone (positive/indefinite). 誰も + negative = nobody. 誰か来た (someone came). 誰も来なかった (nobody came). Think of か as "some-" and も + negative as "no-."
How do I say "whether or not" in Japanese?
Use かどうか: 行くかどうか分からない (I don't know whether they'll go or not). You can also repeat the verb: 行くか行かないか分からない. かどうか is more concise.
Question word + か creates what?