Translation guide
Expresses obligation or necessity. The most common pattern is 〜なければならない, but many variations exist depending on formality, strength, and context. In casual speech, shorter forms like 〜なきゃ or 〜ないと are typical. For external obligations or rules, 〜ことになっている is used.
Express that the speaker feels they must do something, or that it is necessary to do something.
The standard, neutral way to say 'must do'. Used in both speech and writing. Can sound formal in casual conversation.
明日までにレポートを提出しなければならない。
I must submit the report by tomorrow.
I have to study more.
Very similar to 〜なければならない, but slightly more subjective and often used for personal obligations. Interchangeable in most cases.
もう行かなければいけない。
I have to go now.
Casual abbreviation of 〜ないといけない. Very common in everyday speech. Often used without the ending いけない/ならない.
そろそろ帰らないと。
I gotta go home soon.
急がないと遅れるよ。
We have to hurry or we'll be late.
Casual contraction of 〜なければ. Often used without the ending いけない/ならない. Very common in informal speech.
宿題やらなきゃ。
I gotta do my homework.
Formal and emphatic. Often used in writing or official contexts. Slightly stronger than 〜なければならない.
規則を守らなくてはならない。
We must obey the rules.
Formal and subjective. Similar to 〜なくてはならない but more personal.
この問題を解決しなくてはいけない。
We must solve this problem.
Literary and old-fashioned. Used in formal writing or speeches. Equivalent to 〜なければならない.
努力を続けねばならない。
We must continue our efforts.
Express that something must be done because of a rule, schedule, or external expectation.
Indicates a rule, arrangement, or expectation that is decided by someone else or by custom. Not for personal decisions.
会議は毎週月曜日に開かれることになっている。
The meeting is supposed to be held every Monday.
ここでは靴を脱ぐことになっています。
You are supposed to take off your shoes here.
Also used for rules, but can sound like a personal obligation. 〜ことになっている is better for external rules.
パスポートを提示しなければならない。
You must present your passport.
Emphasize that there is no alternative but to do something.
Formal expression meaning 'cannot help but do' or 'have no choice but to do'. Used when the situation forces the action.
その提案を受け入れざるを得なかった。
We had no choice but to accept the proposal.
Casual way to say 'there is nothing but to do'. Implies limited options.
やるしかない。
We just have to do it.
Similar to 〜しかない but slightly more formal. Means 'no other way but to do'.
謝るほかない。
There's nothing to do but apologize.
Express that something must not be done.
Standard way to say 'must not do'. Used in rules and direct prohibitions.
ここで写真を撮ってはいけない。
You must not take photos here.
Formal and strong prohibition. Often used in written rules or official statements.
この情報を外部に漏らしてはならない。
This information must not be leaked outside.
Casual contraction of 〜てはいけない. Used in everyday speech, often with children or friends.
触っちゃだめ！
Don't touch!
Both mean 'must do', but 〜なければならない is slightly more objective and formal, while 〜ないといけない is more subjective and conversational. In practice, they are often interchangeable, but 〜なければならない is preferred in writing and formal speech.
法律を守らなければならない。
We must obey the law. (objective)
そろそろ帰らないといけない。
I have to go home soon. (personal feeling)
English 'must' can sound too strong if directly translated into Japanese in casual contexts. Using 〜なきゃ or 〜ないと is more natural for everyday obligations. Reserve 〜なければならない for formal or serious situations.
In casual speech, the endings いけない/ならない are often omitted after 〜なきゃ, 〜ないと, or 〜なくちゃ. This is very common and natural.
もう行かなくちゃ。
I gotta go.
明日までにこれを終わらせなければならない。
I must finish this by tomorrow.
図書館では静かにしなければいけません。
You must be quiet in the library.
もう行かないと。
I have to go now.