Core Pattern Rule: -잖아 (As you know)
The -잖아 ending is used to state a fact that you believe the listener already knows. It's like adding "as you know," "you know," or "c'mon" to your sentence, confirming a piece of shared information.
Formation
This pattern attaches directly to verb and adjective stems, or to nouns.
Verbs & Adjectives: Attach -잖아(요) directly to the stem, regardless of whether it ends in a vowel or a consonant. This also applies to past tense stems.
가다 (to go) → 가잖아
먹다 (to eat) → 먹잖아
예쁘다 (to be pretty) → 예쁘잖아
말했다 (spoke) → 말했잖아
Nouns:
If the noun ends in a consonant, add -이잖아(요).
학생 (student) → 학생이잖아
If the noun ends in a vowel, add -잖아(요).
친구 (friend) → 친구잖아
내가 말했잖아. / 우린 친구잖아. / 오늘 일요일이잖아.
Native Nuance & Mistakes
The feeling of -잖아 depends heavily on context and intonation. Getting it right is key to sounding natural.
Tone is Everything
-잖아 can be a friendly reminder, but it can also sound like you're scolding, complaining, or being condescending if used improperly.
Friendly Reminder (rising intonation): 오늘 우리 약속 있잖아? (We have plans today, remember?)
Frustration/Scolding (strong, falling intonation): 내가 하지 말라고 했잖아! (I told you not to do that!)
Common Mistake: Using it for New Information
The core of this pattern is shared knowledge. Never use -잖아 to introduce a fact the listener doesn't know. For example, if you tell a new acquaintance, 저는 학생이잖아요 ("I'm a student, as you know"), it sounds strange and presumptuous, as if they were supposed to know that already. Stick to 저는 학생이에요 for new information.
위험하잖아. / 바쁘잖아. / 약속했잖아. / 춥잖아.
How to Respond
When someone uses -잖아 on you, your response usually acknowledges the information they're reminding you of.