You know / Because

The pattern -거든요 is a sentence ending used to provide background information, a reason, or a fact that the listener is likely unaware of. It's often translated as "you see...", "because...", or carries an "actually..." or "for your information..." nuance.

Meaning & Usage

Providing a Reason: It explains the 'why' behind a statement or action. The sentence with -거든요 often comes after a question or before the main point.

Introducing New Information: It's used to state a fact that you assume the other person doesn't know, sometimes to gently correct them or preempt a question.

Formation

It attaches directly to verb and adjective stems.

Verbs/Adjectives: Stem + 거든요

하다 -> 하거든요

바쁘다 -> 바쁘거든요

있다 -> 있거든요

Nouns: Noun + -(이)거든요

학생 (ends in consonant) -> 학생이거든요

거 (ends in vowel) -> 거거든요

Past Tense: Stem + -았/었거든요

했다 -> 했거든요

거짓말이었다 -> 거짓말이었거든요

나 배 안 고프거든. / 사실 거짓말이었거든요. / 제가 좋아하거든요. / 맛있거든요.

-거든요 is a classic conversational connector. It signals that what you're saying is relevant to the situation, but it's not the final point. It creates an expectation that more information is coming or that the listener should now understand the context.

As a Reason

When used as a reason, the sentence with -거든요 often feels slightly incomplete on its own. It naturally invites a follow-up statement.

(왜 이렇게 많이 샀어요?) 제가 좋아하거든요. (Because I like it. [Implication: So I bought a lot.])

(같이 갈 수 있어요?) 저 좀 바쁘거든요. (Actually, I'm a bit busy. [Implication: So I can't go.])

As a Gentle Correction or Statement

When stating a fact the listener doesn't know, it can be used to gently correct a misunderstanding or assert something.

그거 제 거거든요. (That's mine, you know. [So please don't touch it.])

아니거든요. (No, that's not it at all. [You're mistaken.])

나 시간 많거든. / 저 할 수 있거든요. / 그거 내 거거든. / 아직 안 했거든요.

Learners often confuse -거든요 with -잖아요. The key difference is what the speaker assumes the listener knows.

-거든요: Listener doesn't know.

You use this to introduce new information or a reason the listener isn't aware of. It's like saying, "Let me tell you something..." or "The reason is..."

(친구가 왜 피곤해 보이냐고 물어볼 때) 어제 시험공부 했거든요. (I studied for an exam yesterday. [You didn't know this.])

-잖아요: Listener already knows.

You use this to remind or confirm something that both you and the listener are already aware of. It's like saying, "...as you know" or "...don't you remember?"

(어제 같이 공부한 친구에게) 우리 어제 시험공부 했잖아요. 당연히 피곤하죠. (We studied for an exam yesterday, you know. Of course I'm tired. [You know this because you were there.])

Choosing the wrong one can sound strange. Using -거든요 for shared knowledge can sound condescending, while using -잖아요 for new information can be confusing.

저 배 안 고프거든요. / 나 다 알거든. / 그거 제 거거든요.

This pattern has distinct casual and polite forms that are crucial for natural conversation. The script lines demonstrate this clearly.

Casual Form (반말): -거든

Use this form with close friends, family, or people younger than you. Using it with strangers or superiors would sound blunt or rude.

e.g., 나 좀 바쁘거든. (I'm a bit busy, you know.)

Polite Form (해요체): -거든요

This is the standard polite form you should use in most everyday situations with people you don't know well, colleagues, or elders. It's respectful and versatile.

e.g., 저 좀 바쁘거든요. (Actually, I'm a bit busy.)

Notice how simply adding -요 shifts the entire tone of the sentence from informal to polite.

나 남자친구 있거든. / 저 남자친구 있거든요. / 아니거든. / 아니거든요. / 나 다 알거든. / 저 다 알거든요.