Translation guide
Expresses obligation or necessity. Japanese uses several patterns depending on context, formality, and whether the obligation is personal, social, or situational.
Expressing that something must be done, without specifying who imposes the obligation.
Standard pattern for 'must/have to'. Attach to verb negative stem (ない-form minus ない). Formal and written, but also used in speech.
明日までにレポートを提出しなければならない。
I have to submit the report by tomorrow.
I have to practice every day.
Similar to ～なければならない, but slightly more subjective/personal. Often used for things you feel you must do.
もう行かなければいけない。
I have to go now.
Casual equivalent of ～なければいけない. Very common in daily conversation.
早く起きないといけない。
I have to wake up early.
Very casual contraction of ～なければ. Often used without ならない/いけない in informal speech.
宿題やらなきゃ。
I gotta do my homework.
Formal/written pattern, similar to ～なければならない but slightly more emphatic.
規則を守らなくてはならない。
We must follow the rules.
Expressing that you have to do something because of a situation or rule, not personal feeling.
Used when you have no choice but to do something, often reluctantly. Attach to verb negative stem (ない-form minus ない). Formal.
悪天候のため、試合を中止せざるを得なかった。
We had to cancel the game due to bad weather.
Expresses that there is no other choice. Attach to dictionary form of verb. Casual to neutral.
やるしかない。
I have no choice but to do it.
Expressing that you should do something because it's the right thing to do, or expected by society.
Expresses 'should/ought to' based on moral duty or common sense. Attach to dictionary form of verb. する becomes すべき.
約束は守るべきだ。
You should keep your promises.
Used for general social expectations or common sense. Attach to dictionary form.
年上には敬語を使うものだ。
You should use polite language with elders.
Expressing prohibition: 'must not do' or 'have to not do'.
Standard prohibition pattern. Attach to て-form of verb.
ここで写真を撮ってはいけない。
You must not take photos here.
Formal/written prohibition, stronger than ～てはいけない.
秘密を漏らしてはならない。
You must not leak secrets.
Casual prohibition. Contraction of ～てはだめ.
触っちゃだめ！
Don't touch!
Both mean 'must/have to', but なければならない is more formal and objective, while ないといけない is more casual and subjective. In daily conversation, ないといけない or its contracted forms (なきゃ, なくちゃ) are more natural.
レポートを出さなければならない。（フォーマル）
I have to submit the report. (formal)
レポート出さないといけない。（カジュアル）
I gotta submit the report. (casual)
English 'have to' is often used for mild obligations or suggestions. In Japanese, using strong obligation patterns like ～なければならない for minor things can sound overly dramatic. For light suggestions, consider ～たほうがいい (should) or ～たらどう？ (why don't you?).