“Nande・Dōshite・Naze”: The Three ‘Why' Brothers [JLPT N5]
By Nihongo to Japan · Updated July 3, 2026
「なんで遅れたの？」「どうして泣いてるの？」「なぜこうなった？」 — a full comparison of tone, situation, and formality.
“Nande・Dōshite・Naze”: The Three ‘Why' Brothers
These three all mean “why,” but differ in tone and formality: なんで = most colloquial, casual (among friends: なんで遅刻したの? = why were you late?); どうして = neutral, general (used colloquially too, a bit more polite: どうして泣いてるの? = why are you crying?); なぜ = more formal, written (papers, formal settings, written analysis: なぜこの現象が起きるのか = why this phenomenon occurs). Formality: なぜ > どうして > なんで. ⚠️ なんで most colloquial, なぜ most formal, どうして in between. ⚠️ Note: 「どうしても」 = no matter what (not どうして + も); 「なんで」 can also ask the means (by what, by context).
🧠 Core nuance: all ask ‘why,' differing in tone and formality
The core is all three ask the reason ‘why,' differing in tone, formality, situation: ① なんで — most colloquial, casual, close (everyday conversation among friends, family: なんで来なかったの? = why didn't you come?), with a casual, even slightly emotional tone; ② どうして — neutral, general, used colloquially but a bit more polite, more measured than なんで (どうして遅れたんですか = why were you late?), usable in a wider range of situations; ③ なぜ — most formal, written, objective (papers, reporting, formal analysis, written thought: なぜこの現象が起きるのか分析する = analyze why this phenomenon occurs). ⚠️ Formality order: なぜ (most formal) > どうして (neutral) > なんで (most colloquial). ⚠️ Judging the situation: friends chatting use なんで/どうして, formal/written/papers use なぜ. ⚠️ Important distinction: 「どうしても」 = no matter what, by any means (どうしても諦めない = won't give up no matter what), not the question 「どうして」; 「なんで」 in some contexts can ask the means (by what, なんで行く? = go by what?, but usually asks the reason). A basic N5 conversational question word.
📌 The Three Compared
| Expression | Tone/Formality | Situation |
|---|---|---|
| なんで | most colloquial, casual | friends, family (なんで?) |
| どうして | neutral, general | colloquial too, a bit polite |
| なぜ | most formal, written | papers, reporting, formal analysis |
💬 Example Sentences
- (among friends) なんで遅刻したの?(Why were you late?) — なんで (most colloquial)
- どうして泣いてるの? 何かあった?(Why are you crying? Did something happen?) — どうして (neutral)
- レポートで「なぜこの現象が起きるのか」を分析する。(In the report, analyze ‘why this phenomenon occurs.') — なぜ (formal written)
- なぜこんな結果になったのだろう。(Why did it turn out like this, I wonder.) — なぜ (introspective, written style)
- どうしてそう思うんですか?(Why do you think so?) — どうして (a bit polite)
🔄 Compare: なんで vs どうして vs なぜ vs どうしても
| Expression | Nuance | Example |
|---|---|---|
| なんで | “why” (most colloquial, casual) | なんで遅刻? |
| どうして | “why” (neutral, general, a bit polite) | どうして泣くの? |
| なぜ | “why” (most formal, written) | なぜ起きるのか |
| どうしても | “no matter what” (≠ どうして + も) | どうしても諦めない |
⚠️ Common Mistakes
- Formality: なぜ (most formal written) > どうして (neutral) > なんで (most colloquial); papers use なぜ, friends use なんで.
- どうしても ≠ どうして + も: どうしても = no matter what (どうしても諦めない), not ‘why also.'
- Choose by situation: formal/written use なぜ; everyday speech use なんで/どうして.
- なんで can ask the means: なんで in some contexts can ask the means (by what), but usually asks the reason.
💡 Nuance & When to Use
「なんで・どうして・なぜ」 all ask ‘why,' differing in tone and formality: なんで (most colloquial, casual, among friends), どうして (neutral, general, a bit polite), なぜ (most formal, written, papers/reporting). Formality: なぜ > どうして > なんで. ⚠️ Situation: friends use なんで/どうして, formal writing uses なぜ. ⚠️ Note 「どうしても」 = no matter what (≠ どうして + も). A basic N5 conversational question word. A must.
🎯 JLPT Exam Tips
- N5 conversation: なんで (most colloquial), どうして (neutral, a bit polite), なぜ (most formal, written); all ask ‘why.'
- Formality: なぜ > どうして > なんで; papers use なぜ, friends use なんで.
- Note: どうしても = no matter what (≠ どうして + も); choose by situation.
🖊️ Practice Quiz
Q1. Casual conversation between friends: 「___遅刻したの？」(why were you late?) What's most natural?
(A) なぜ (B) どうして (C) なんで (D) both B and C are natural
Q2. Academic paper/report: 「___この現象が起きるのか分析する。」What's most suitable?
(A) なんで (B) どうして (C) なぜ (D) all the same
Q3. What does 「どうしても諦めない」 mean?
(A) why won't you give up?
(B) won't give up no matter what (絶対に諦めない)
(C) you should give up
(D) might give up
Q4. In what context is なぜ most suitable: 「___こんな結果になったんだろう。」?
(A) silent self-reflection (written style)
(B) casual chat with a friend
(C) asking a child
(D) all the same
Q5. What is the order of formality of なんで・どうして・なぜ (most formal first)?
(A) なぜ > なんで > どうして
(B) なんで > どうして > なぜ
(C) なぜ > どうして > なんで
(D) どうして > なぜ > なんで
Answer Key
1. (D) both B and C are natural ── between friends, なんで (most colloquial) and どうして (neutral colloquial) are both natural; なぜ is too formal for casual talk.
2. (C) なぜ ── papers/written text use なぜ (most formal, written).
3. (B) ── どうしても ＋ negative = no matter what, won't … (絶対に諦めない).
4. (A) ── なぜ suits written-style, silent self-reflection.
5. (C) なぜ > どうして > なんで ── なぜ (most formal) > どうして (neutral) > なんで (most casual).