Не vs Нет: How Does Russian Negation Work?
Distinguish ordinary not from no and there is not, including the genitive after нет.
RU009 · RU · A1 / A2 · grammar, cases
The question
Why is it Я не знаю but У меня нет времени?
Не is the usual particle for negating a verb, adjective or another phrase: Я не знаю (I don't know), Это не трудно (This isn't difficult). Нет can stand alone as 'no', or express nonexistence or absence, often with a genitive noun: У меня нет времени (I don't have time).
Compare the meanings
| Russian | English | What is negated |
|---|---|---|
| Нет, спасибо. | No, thank you. | Answer |
| Я не читаю. | I'm not reading. | Verb |
| Это не мой дом. | This isn't my house. | Identification |
| Здесь нет воды. | There is no water here. | Existence or availability |
The genitive is standard with existential нет: нет книги (there is no book), нет друзей (there are no friends). But negating a verb does not universally switch its object into the genitive: Я не читаю эту книгу (I'm not reading this book) has an accusative object. Russian can also use double negation: Я ничего не знаю (I don't know anything).
Common mistake
Avoid *Я нет знаю. Use Я не знаю. And don't assume every noun after не must be genitive: the grammatical construction determines the case.
Remember
Не negates words or predicates; нет is 'no' or 'there is none', commonly with genitive for absence.