Translation guide
The English word 'need' can express necessity, requirement, or lack. In Japanese, it is expressed through various adjectives, verbs, and grammatical patterns depending on whether you are talking about something necessary, something you must do, or something lacking.
The most common and versatile word for 'need' or 'necessity'. Can be used as a noun or na-adjective.
水は生きるために必要です。
Water is necessary to live.
もっと情報が必要だ。
I need more information.
A common verb meaning 'to be needed' or 'to be necessary'. Used for concrete things.
お金が要る。
I need money.
この仕事には経験が要りますか？
Is experience needed for this job?
Pattern meaning 'need ~'. The thing needed is marked with が.
あなたの助けが必要です。
I need your help.
Expresses obligation or necessity to do something ('must', 'have to'). Often corresponds to 'need to'.
明日早く起きなくてはいけない。
I need to get up early tomorrow.
宿題をしなければならない。
I need to do my homework.
Literally 'there is a need to ~'. More formal than 〜なくてはいけない.
早急に対策を講じる必要がある。
We need to take measures immediately.
Expressing that something is lacking or desired.
Means 'not enough', 'insufficient'. Used when something is lacking in quantity.
Means 'want' or 'desire'. Can sometimes overlap with 'need' when expressing a strong desire for something necessary.
Means 'indispensable', 'essential'. Stronger than 必要.
彼はチームに欠かせない存在だ。
He is indispensable to the team.
Expressing that someone must do something.
Casual/contracted form of 〜なくてはいけない. Very common in spoken Japanese.
もう行かないといけない。
I need to go now.
Very casual contraction of 〜なければ. Often used without the ending いけない in informal speech.
勉強しなきゃ。
I need to study.
必要 is a na-adjective/noun meaning 'necessity' and can be used for abstract concepts. 要る is a verb meaning 'to be needed' and is typically used for concrete, tangible things. 必要 can also be used with がある to mean 'there is a need to do something'.
English 'need' is a verb, but Japanese often expresses it with adjectives (必要) or intransitive verbs (要る). Avoid directly translating 'I need X' as '私はXを必要する' — it's unnatural. Use 'Xが必要だ' or 'Xが要る' instead.
ちょっと考えないといけない。
I need to think about it.
I need a new computer. (lit. I want a new computer.)