до́лжен vs ну́жно

dolzhen vs nuzhno — must vs need/is necessary

What it really means

До́лжен is the short adjective meaning “must,” “ought to,” or “is obliged to.” It agrees with the person in gender and number: я до́лжен (masculine), я должна́ (feminine), мы должны́. It frames the obligation as belonging to a particular subject, whether because of duty, rules, or expectation.

Ну́жно is an impersonal predicative meaning “it is necessary” or “one needs to.” It does not identify a grammatical subject in the nominative; the person who needs to act is commonly in the dative: мне ну́жно рабо́тать. Use до́лжен for a person's obligation and ну́жно for a necessity or instruction, although everyday contexts can make the difference subtle.

Examples in natural speech

Я до́лжен закончить рабо́ту сего́дня.
I must finish the work today.
Она́ должна́ позвони́ть ма́ме.
She has to call her mother.
Мне ну́жно купи́ть хле́б.
I need to buy bread.
Ну́жно прове́рить докуме́нты.
The documents need to be checked.
Мы должны́ быть осторо́жными.
We must be careful.

Common mistakes

Do not forget agreement with до́лжен: женщина́ должна́, де́ти должны́. With ну́жно, use the dative for the person who needs to act—мне, тебе́, ему́—and do not make that person a nominative subject in the impersonal pattern.

Memory tip

До́лжен wears the obligation on a person; ну́жно describes what necessity requires.

Frequently asked questions

Is до́лжен stronger than ну́жно?

Often it sounds more like a personal duty, but context controls strength; ну́жно can also express a firm requirement.

Can I say мне до́лжен?

No. Say я до́лжен (“I must”) or мне ну́жно (“I need to”). The dative мне belongs to the impersonal construction.

How do I negate these words?

Не до́лжен means “must not/is not obliged,” while не ну́жно usually means “it is not necessary”; нельзя́ is common for “must not/one may not.”

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