-잖아요
Used to provide a reason or reminder based on shared knowledge — something both the speaker and listener already know. Carries a slight tone of surprise or mild reproach that the listener might have forgotten.
Summary
Equivalent
You know... / As you know... / Don't you know that...?
Also: -거든요 (Background info the listener may NOT know) · -(으)니까 (Strong logical reason)
Example
You know how congested the traffic is there. It would be better to take the subway.
거기는 교통이 복잡하잖아요. 지하철을 타고 가는 게 낫겠어요.
Grammar rules
- Unlike '-거든요' (new info), '-잖아요' is for SHARED info.
- It implies: 'You already know this, right?' Often used to gently correct or remind someone.
- Can carry a tone of slight reproach or reminder if overused. Use carefully in formal situations.
오늘 우리 약속 있잖아요. (You know, we have plans today.) — reminding the listener
Patterns
Verbs
Present · Verb Stem + 잖아요
Adjectives
Present · Adjective Stem + 잖아요
Nouns
Present · Noun + 잖아요
Example sentences
You know how congested the traffic is there. It would be better to take the subway.
거기는 교통이 복잡하잖아요. 지하철을 타고 가는 게 낫겠어요.
You know Sumi is good at cooking. Let's ask her.
수미 씨가 요리를 잘하잖아요. 한번 부탁해 봐요.
Tomorrow is a public holiday, you know. They'll be closed.
내일이 공휴일이잖아요. 문을 닫을 거예요.
Conversation
A: Why didn't you tell me first?
왜 저한테 먼저 말 안 했어요?
B: You know how busy you are. That's why I couldn't say anything.
당신이 바쁘잖아요. 그래서 말 못 했어요.
Practice
Fill in the blank
Select the correct reminder/shared-knowledge form.
Shared knowledge of difficulty.
Shared knowledge of a person.