Без понятия, даже не знаю.

Literally, без понятия means without an idea/notion. In real usage, though, it is a very common idiomatic expression meaning I have no idea.

It is felt as a set phrase, so learners should remember it as a chunk rather than trying to build it from scratch every time.

Because the preposition без always takes the genitive case.

The dictionary form is понятие.
Its genitive singular form is понятия.

So:

• понятие = idea, notion
• без понятия = without an idea

This is one of the first case patterns learners meet in Russian:

• без сахара = without sugar
• без воды = without water
• без понятия = no idea / without a clue

Yes, you could think of an underlying я, but Russian often omits subject pronouns when they are obvious from context.

So Без понятия, даже не знаю naturally implies:

• Я без понятия, я даже не знаю

But saying я would usually sound unnecessary unless you want contrast or emphasis.

This kind of omission is very normal in Russian conversation.

They are a little repetitive, but in a very natural, conversational way.

Using both gives extra emphasis, like saying:

• No idea, I don’t even know
• I have absolutely no clue

So the speaker is not just stating ignorance once; they are reinforcing it. This is common in casual speech.

Даже means even, and here it strengthens the negation.

• не знаю = I don’t know
• даже не знаю = I don’t even know

In context, даже adds a sense of stronger uncertainty, sometimes with a tone of helplessness, surprise, or mild frustration.

Без понятия is informal / colloquial. It is very common in everyday speech and texting.

It is fine with friends, in casual conversation, and in informal writing.

In more formal situations, people might prefer things like:

• не знаю = I don’t know
• не имею понятия = I have no idea
• мне неизвестно = it is unknown to me / I do not know

So без понятия is natural, but not especially formal.

Yes. Very often it stands alone.

For example:

• Где он?
  Без понятия.

That is completely natural and means No idea.

Russian often allows short fragment answers like this, especially in conversation.

Both mean I have no idea, but they differ a little in structure and feel.

• без понятия = literally without an idea; short, punchy, conversational
• понятия не имею = literally I do not have an idea; also very common, slightly fuller as a sentence

Both are idiomatic and natural.
A learner will hear both often.

For example:

• Без понятия.
• Понятия не имею.

Both are good casual answers.

The comma separates two parts that are spoken with a pause:

• Без понятия
• даже не знаю

The first part is a short idiomatic fragment, and the second is a full verbal clause. In speech, it sounds like two quick pieces of one reaction.

So the comma reflects natural intonation: first a blunt answer, then an added clarification or emphasis.

Yes, very natural. It sounds like something a native speaker could easily say in conversation.

It has a casual spoken feel: short, emotional, and slightly emphatic. A learner should recognize it as everyday conversational Russian rather than textbook-style formal language.