also: なくてもよい
expression
need not; don't have to
Attaches to the negative stem of a verb or adjective to express lack of obligation or necessity. Very common in everyday speech.
今日は残業しなくてもいいですよ。
You don't have to work overtime today.
そんなに急がなくてもいい。
You don't need to hurry so much.
expression
need not have; need not exist
Used when saying that something does not need to be present or exist. Often appears in conditional or hypothetical contexts.
See also: 無い
特別な道具はなくてもいい。
You don't need any special tools.
理由がなくてもいいから、とにかくやってみよう。
You don't need a reason; let's just give it a try.
Formed from the negative stem of a verb/adjective + ても (even if) + いい (good), literally 'it's good even if not...'. The kanji spelling 無くても良い uses 無い (not exist) and 良い (good).