Have to and Must
This page covers two common ways to express that something has to be done or must be done:
なければ+いけない
なければ+ならない
なければいけない
Have to do/be
い Adjectives/Verbs: ない form →ない→ければいけない
な Adjectives/Nouns: +じゃなければいけない
なければいけない literally means “If (subject) doesn’t, then its not allowed”. Put into simpler English, it just means that you “have to do/be” something.
This pattern may be used to force or suggest to the listener what to do. Because of this, it is more like a strong suggestion.
The opposite of this pattern is てはいけない (Not なくてはいけない)
Examples
- 勉強しなければいけない – You have to study. (Strong suggestion)
- 明日出勤しなければいけない – You have to come into work tomorrow. (Command)
- 女性じゃなければいけない – It needs to be a woman. (to do/fulfill something, NOT “probably is a woman”)
- つよかなければいけない – Needs to be strong.
- ホテルは静じゃなければいけない – A hotel has to be quiet.
なければならない
Must do/be
い Adjectives/Verbs: ない form →ない→ければならない
な Adjectives/Nouns: +じゃなければならない
なければならない has the same meaning as なければならない except:
- It is used towards people in general (not anyone or thing specific)
- It is used in laws and legal statements.
- It is used when the reason is based on morals, rules, or customs.
- It is used when there is no choice or ability to change it at all.
Examples
- 税金を払わなければならない – You must pay your taxes.
- 道路の左側を使わなければならない – You must use the left side of the road.
- 先生は平等じゃなければならない – A teacher must be impartial.
Variations
Some Possible Variations:
なきゃいけない・なきゃならない
なくてはいけない・なくてはならない
なくちゃいけない・なくちゃならない
なくてはだめ・なくちゃだめ
しないといけない・しないとだめ
Sound Abbreviations
なければいけない・ならない may be, and often are, abbreviated by shortening なければ to なきゃ
- しなきゃいけない – Have to do.
- 待たなきゃならない – Must wait.
ては may become ちゃ with なくては statements (see below)
だめ
だめ may be substituted for いけない, though it is a bit less formal.
と
The と conditional may be used in place of ば, however it may not be used with ならない, and has the normal nuance of the conditional と (Naturally, soon)
- 勉強しないといけない
なくては
The negative version of てはいけない, なくてはいけない may also be used.
なくては has the same meaning as なければいけない, but is very slightly stronger.
The reason for this is that ば is an “if” statement, usually implying a choice, while ては is a statement with no choice.
- 勉強しなくてはいけない – Not studying is bad.
- 勉強しなければいけない – If you don’t study, it’s bad.
- 言わなければいけない – If you don’t say something, it’s bad.
- 言わなくてはいけない – Not saying something is bad.
- 飲まなければいけない – It’s bad if you don’t drink it. (you should)
- 飲まなくてはいけない – It’s bad if you don’t drink it. (you have to)
If I were pressed for one more difference, it would be that なくてはいけない sounds like the other person was planning on not doing something, and you are correcting them, sort of like “you can’t not do it”
References
Goo 辞書 (All Japanese)
Quora (English, but barely helpful)