нужно / надо - merely a matter of politeness?
Quite used to seeing both these forms about; wondered as to any semantic difference as they've appeared to be used interchangeably.
Looking elsewhere, the consensus over on Word Reference seems to be that it's a matter of politeness. Astonishingly, they managed to argue quite a lot there despite this overall consensus.
Is there anything more I should know? And if it's about politeness, is it also about the severity of the need?
Мне нужны деньги / Мне надо кислород?
Is it reasonable and polite to use надо when one is talking about an absolutely critical need, perhaps being more appropriate in those cases than нужно?
"Надо" is a colloquial form derived from the obsolete word "надобно". This fact may be a root for the claims that it's a less polite word, which is, in my opinion, actually not; it's just some set expressions with this word may be impolite or even rude (e.g. "так ему и надо", "оно мне надо?"; however, you can sometimes hear the same expressions with the word "нужно" and exactly the same meaning).
"Надо" is used with infinitives usually, i.e. надо сказать (need to be said), надо сделать (need to be done), etc.
"Нужно" has the same meaning and it is your safe word of choice. It is used with both infinitives and nouns, i.e. нужно сделать, нужны деньги.
Both words can mean a need or a must, depending on the context.
One more thing. "Надо" with nouns is usually used only colloquially. I.e. "мне нужны деньги" = "мне надо денег", "мне нужна вода" = "мне надо воды", "мне нужен воздух" = "мне надо воздуха". Nouns with "надо" use genitive case.
I agree about politeness. Moreover I'd say надо is a demand and нужно is a request. Although your example "Мне нужны деньги / Мне надо кислород" does not fit for this "rule" мне нужны деньги sounds good. Even I need them very much or I spent the last penny for bread and I'm hungry I will not say мне надо деньги. This sounds like grammatical mistake. Better мне надо иметь(получить) деньги. Again Мне нужен кислород sounds better. Even when I'm diving under water I'd use нужен. Мне надо получить(вдохнуть) кислород sounds good.
I hope proffesional teachers tell more about this.
PS. your link is not correct from my computer (
Why then нужен for needing oxygen, but надо for needing to breathe it?
I had not seen either of them as a demand or a request, but a statement in each case :s
If you'd use "Мне надо получить(вдохнуть) кислород", is it then about needing the verb rather than needing the noun?
As for the link, yes, it appears the parsing for this site eats anything that's not in Roman letters, making it necessary to copy and paste any such link. For those for whom this is inconvenient, here's a Tiny.cc version:
In general, надо is used with infinitives. Нужно is also used with infinitives + you can use нужен/нужна/нужно/нужны with a noun depending on its gender and number.
Occasionally, you will see some speakers use надо with nouns but it is tricky to make it sound natural... It somewhat works with Genitive or negation when you need some substance, real or abstract—usually in colloquial speech.
- ? Нам надо картошки/воды/сока.
- Нам надо больше воды/ ещё немного времени.
- Не надо паники!
Otherwise it will sound as a mistake, though with neuter nouns it may take a listener some time to register something's off. With other nouns it is glaringly obvious because the gender of надо will not match the gender of a noun. Which is natural, given that надо does not have gendered forms:)
look, I'm not a teacher. I'm not sure that considerable amount of russian speaking people do not say мне надо кислород. For me it sounds like a very flimsy mistake. I'm trying to think some other examples and see that you are rather right надо + verb and нужно +noun or verb. Sorry that I can't explain more explicity.
I think the difference is akin to that between English modal verbs: I need money. vs. I must breath.
To add to all those elucidating replies: the big difference there is with negation. While "не нужно" rather means "don't have to" or "don't need to", "не надо" usually means "must not".