expression, i-adjective
Attaches to the negative base of a verb (ない-form) to express obligation or necessity. Equivalent to なければならない, but slightly more colloquial.
See also: なくてはいけない
明日までにレポートを出さないといけない。
I have to submit the report by tomorrow.
もう行かないといけない時間だ。
It's time I must go.
expression, i-adjective
indispensable; absolutely necessary
Used when something itself is essential, not as an auxiliary. Often appears in statements like ～がないといけない (without ~ it's no good).
See also: なくてはいけない
この仕事には経験がないといけない。
Experience is indispensable for this job.
健康でないといけない。
You must be healthy. (lit. It is necessary to be healthy.)