English wraps a yes/no question inside a bigger sentence with whether or if: "I don't know whether he'll come." Japanese does it with 〜かどうか, a tidy little frame meaning "whether or not." You take the yes/no question, put it in plain form, cap it with か, add どうか ("or how"), and drop the whole package into a slot in the main sentence. The frame is easy; the one thing that catches English speakers is a spelling-out detail — what happens to だ — and it turns out to follow a rule you already know from asking direct questions.
The frame: [plain clause] + か + どうか
The shape is completely regular:
[ yes/no question in plain form ] か どうか [ main verb ]
The embedded clause behaves like the object of the main verb — verbs of knowing, checking, and wavering: 分かる, 知る, 確かめる, 確認する, 迷う, 心配する.
行くかどうか分からない。
iku ka dō ka wakaranai
I don't know whether I'll go.
彼が来るかどうか分からない。
kare ga kuru ka dō ka wakaranai
I don't know whether he'll come.
これでいいかどうか教えてください。
kore de ii ka dō ka oshiete kudasai
Please tell me whether this is okay.
Literally, どうか is "or how," so かどうか is "…か? or how [not]?" — i.e. "whether or not." The internal question is asked and its answer left open; the main verb comments on that open question ("don't know," "will check," "am wavering").
参加するかどうか迷っている。
sanka suru ka dō ka mayotte iru
I can't decide whether to take part.
正しいかどうか確認する。
tadashii ka dō ka kakunin suru
I'll check whether it's correct.
The key detail: だ is dropped before か
Here is the point to nail down. When the embedded question is built on a noun or a na-adjective, you might expect the plain copula だ to appear before か. It does not. だ is deleted before this embedded か — for exactly the same reason it is deleted in a direct question.
Recall how a direct question works: the polite 学生ですか drops to plain 学生か, never ×学生だか. That "no だ before か" rule is not special to questions at the end of a sentence — it rides along into the embedded question untouched:
彼が犯人かどうかまだ分からない。
kare ga hannin ka dō ka mada wakaranai
We still don't know whether he's the culprit.
この水が安全かどうか調べた。
kono mizu ga anzen ka dō ka shirabeta
I checked whether this water was safe.
犯人 is a noun and 安全 is a na-adjective, yet neither shows だ — it is 犯人かどうか and 安全かどうか, never ×犯人だかどうか. Verbs and i-adjectives, by contrast, attach directly because they are already complete plain-form predicates:
| Predicate type | Plain form | Embedded |
|---|---|---|
| verb | 来る | 来るかどうか |
| i-adjective | いい | いいかどうか |
| na-adjective | 安全 | 安全かどうか |
| noun | 学生 | 学生かどうか |
More verbs that host かどうか
The embedded question slots in wherever a main predicate can take a question as its content — asking, worrying, remembering, mattering:
予約が必要かどうか聞いてみます。
yoyaku ga hitsuyō ka dō ka kiite mimasu
I'll ask whether a reservation is needed.
間に合うかどうか、ちょっと心配です。
maniau ka dō ka, chotto shinpai desu
I'm a little worried about whether we'll make it in time.
本当かどうか確かめたほうがいい。
hontō ka dō ka tashikameta hō ga ii
You'd better check whether it's true.
味見して、塩が足りるかどうか見て。
ajimi shite, shio ga tariru ka dō ka mite
Taste it and see whether there's enough salt.
When you can drop どうか
If the point is simply "whether (I don't know the answer)," you may leave off どうか and keep just か — especially in speech. かどうか makes the "or not" fully explicit; bare か is a touch lighter.
明日晴れるか分からない。
ashita hareru ka wakaranai
I don't know whether it'll be sunny tomorrow.
But once you spell out the alternative yourself (whether A or B), you drop どうか and instead pair two clauses with か: 行くか行かないか ("whether to go or not"). And crucially, どうか is only for yes/no questions. The moment a question word (何, どこ, 誰…) is involved, you switch to the wh-frame with plain か and no どうか — covered on embedded wh-questions.
かどうか vs と: "whether" is not "that"
English if/whether and that both feel like "connectors," so learners reach for the quotation particle と where かどうか is needed. But と reports a settled statement ("he said that he'd come," 来ると言った), while かどうか marks an open question ("whether he'll come"). If the content is a decided fact you are relaying, use と; if it is an unresolved yes/no, use かどうか.
Common mistakes
Mistake 1 — Inserting だ before か with a noun. The single most common error; だ is deleted before か.
❌ 彼が学生だかどうか分からない。
Wrong — だ must drop before か. It's 学生かどうか, just like the direct question 学生か (not 学生だか).
✅ 彼が学生かどうか分からない。
kare ga gakusei ka dō ka wakaranai
I don't know whether he's a student.
Mistake 2 — Same error with a na-adjective. na-adjectives behave like nouns here: no だ.
❌ この店が有名だかどうか知らない。
Wrong — na-adjectives also drop だ before か. It's 有名かどうか.
✅ この店が有名かどうか知らない。
kono mise ga yūmei ka dō ka shiranai
I don't know whether this shop is famous.
Mistake 3 — Using と for "whether." と relays a settled statement, not an open yes/no question.
❌ 彼が来ると分からない。（「来るかどうか」のつもりで）
Wrong for 'whether he'll come' — と marks a settled statement. An open yes/no needs かどうか.
✅ 彼が来るかどうか分からない。
kare ga kuru ka dō ka wakaranai
I don't know whether he'll come.
Mistake 4 — Adding どうか to a wh-question. どうか is strictly for yes/no; a question word already carries the "which/what" openness.
❌ 何を買うかどうか決めた。
Wrong — with a question word (何), drop どうか. It's 何を買うか決めた ('decided what to buy').
✅ 何を買うか決めた。
nani o kau ka kimeta
I've decided what to buy.
Key takeaways
- Embed a yes/no question with [plain clause] + か + どうか ("whether or not"), slotting it as the object of 分かる, 確かめる, 迷う, and the like.
- だ is dropped before か — 学生かどうか, 安全かどうか, never ×学生だかどうか. It is the same "no だ before か" rule as in direct questions.
- Verbs and i-adjectives attach directly (来るかどうか, いいかどうか); nouns and na-adjectives simply lose their だ.
- You may drop どうか in speech (来るか分からない), but かどうか is yes/no only — a question word switches you to the wh-frame.
- Use かどうか for an open yes/no, と for a settled statement — "whether" is not "that."
Now practice Japanese
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning Japanese→Related Topics
- Embedded Wh-Questions: 〜か + 疑問詞N3 — To embed a content question — 'I decided what to buy' — Japanese leaves the question word exactly where it stands and closes the clause with か; there is no wh-fronting, so English speakers must suppress the reflex to yank the question word to the front.
- Quotation with とN4 — と marks the boundary of a thought or utterance treated as content, closing a quoted clause before verbs of saying, thinking, and calling — and by extension introducing intentions, names, and even sounds.
- Embedded and Subordinate ClausesN4 — How Japanese builds a clause into a larger one — as a complement, an adverbial, or a noun-modifier — always right-headed, with the subordinator at the clause's end and the plain form inside.